Photovoltaic Materials, Devices, and Technologies

Optical simulations of microcrystalline silicon solar cells applying plasmonic reflection grating back contacts

[+] Author Affiliations
Ulrich W. Paetzold, Etienne Moulin, Bart E. Pieters, U. Rau, R. Carius

IEK5-Photovoltaik, Forschungszentrum Juelich, D-52425 Juelich, Germany

J. Photon. Energy. 2(1), 027002 (Jun 11, 2012). doi:10.1117/1.JPE.2.027002
History: Received January 9, 2012; Revised March 21, 2012; Accepted April 17, 2012
Text Size: A A A

Open Access Open Access

Abstract.  Light trapping is a key issue for high efficiency thin-film silicon solar cells. The authors present three-dimensional electromagnetic simulations of an n-i-p substrate-type microcrystalline silicon solar cell applying a plasmonic reflection grating back contact as a novel light-trapping structure. The plasmonic reflection grating back contact consists of half-ellipsoidal silver nanostructures arranged in square lattice at the back contact of thin-film silicon solar cells. Experimental results of prototypes of microcrystalline silicon thin-film solar cells showed significantly enhanced short-circuit current densities in comparison to flat solar cells and, for an optimized period of the plasmonic reflection grating back contact, even a small enhancement of the short-circuit current density in comparison to the reference cells applying the conventional random texture light-trapping structure. The authors demonstrate a very good agreement between the simulated and experimental spectral response data when taking experimental variations into account. This agreement forms an excellent basis for future simulation based optimizations of the light-trapping by plasmonic reflection grating back contacts. Furthermore, from the simulated three-dimensional electromagnetic field distributions detailed absorption profiles were calculated allowing a spatially resolved evaluation of parasitic losses inside the solar cell.

Figures in this Article

Light trapping is essential for high efficiency thin-film silicon solar cells made of amorphous (a-SiH) and microcrystalline silicon (µc-SiH).1 To date, the conventional light-trapping concept in thin-film silicon solar cells applies randomly textured substrates and reflective back contacts in order to scatter and diffract incident light. The resulting light path enhancement increases the absorption of incident light inside the optically thin a-SiH and µc-SiH absorber layers. As a result, the performance of the solar cells is improved. Various types of substrates, materials and processes have been investigated in the past to realize the randomly textured substrates. Prominent examples of randomly textured substrates implemented in state of the art solar cells are wet-chemically etched, sputtered ZnOAl layers or as-deposited grown SnO2 or ZnOAl layers.24 Despite the variety of investigated random textures, especially for longer wavelengths the spectral response of thin-film silicon solar cells remains significantly below the potential of, e.g., crystalline silicon solar cells.5 For this reason, several new light-trapping concepts are the focus of recent studies.610

One of these new light-trapping concepts applies localized surface plasmon polariton (LSPP)-induced scattering of incident light at metal nanostructures. LSPP resonances denote coherent collective oscillations of the free electron gas in metal nanostructures embedded in a dielectric. At Ag nanoparticles or nanostructured Ag layers, light can couple efficiently to LSPP resonances.11 A subsequent radiative decay of plasmonic resonances, which dominates for large Ag nanostructures (radius >50nm), can cause very efficient scattering of the incident light. This way, Ag nanostructures which exhibit LSPP resonances can serve as sub-wavelength scattering components that couple incident propagating light into thin a-SiH or µc-SiH absorber layers. Depending on the position of the Ag nanostructures within the layer stack of the solar cell, different concepts have been suggested in literature to make use of the LSPP-induced scattering. For example, Ag nanostructures placed at the front interface of solar cells have been proposed to reduce the initial reflection at the front interface of the solar cell.12 In between two component cells in a multijunction solar cell, LSPP-induced scattering at Ag nanoparticles can be used in an intermediate reflector to match the photocurrent of the single component solar cells.13 At the rear side of the solar cell, nanostructured Ag back contacts have been applied in order to scatter incident light such that the light is guided in the absorber layers of the solar cell.1417 Regular arrangements of plasmonic nanostructures, which are also in the focus of this study, have been investigated for a-SiH solar cells in the pioneering work of Ferry et al.14,15 Also for µc-SiH solar cells a significant light-trapping potential has been identified in literature.10,18,19 In this contribution, such a regularly nanostructured ZnOAl/Ag back contact for µc-SiH solar cells is investigated regarding its light-trapping effect and impact on the solar cell performance.

In a recent study we have investigated the influence of the size, the shape and the embedding layer stack on the LSPP resonances of isolated and periodically arranged semi-spherical Ag nanostructures at the back contact in detail by means of simulations.19 The Ag nanostructures were optimized with respect to their ability to scatter incident light at low optical losses into large angles into the µc-SiH absorber layers of the solar cell. One of the very promising geometries identified are half-spherical Ag nanostructures of radii above 100 nm arranged in square lattice at the back contact of µc-SiH thin film solar cells. We call the corresponding Ag surface geometry a plasmonic reflection grating back contact. In a second recent study, we have presented first prototypes of n-i-p substrate-type µc-SiH thin-film solar cells fabricated on plasmonic reflection grating back contacts.20 A schematic cross-section of these solar cells is presented in Fig. 1. Enhanced short-circuit current densities Jsc have been measured for the solar cells with the plasmonic reflection grating back contact in comparison to flat solar cells.20 For wavelengths from 550 to 1100 nm, the corresponding external quantum efficiency (EQE) was enhanced significantly in comparison to the EQE measured for the solar cell deposited on the flat substrate. Most importantly, for a 500 nm period of the plasmonic reflection grating even in comparison to the conventional light-trapping concept an enhancement of photocurrent was measured (see Table 1). For this reason, plasmonic reflection grating back contacts are very promising light-trapping devices for future thin-film silicon solar cells.

Graphic Jump LocationF1 :

(a) Schematic cross section of the n-i-p substrate-type solar cell deposited on a plasmonic reflection grating back contact. The three-dimensional layer stack of the front contact and reflection grating back contact is shown schematically in (b) and (c), respectively. (d) Scanning electron microscopy image of the nanostructured Ag surface at the back contact of the solar cell.

Table Grahic Jump Location
Table 1Short-circuit current densities Jsc of n-i-p substrate-type μc-SiH thin-film solar cells deposited on three different types of substrates: (i) a flat back contact, (ii) a random texture back contact, and (iii) a plasmonic reflection grating back contact of 500 nm period.20

In order to obtain a more detailed insight into the optics of the solar cells with integrated plasmonic reflection grating back contact, we present in this contribution simulations of complete n-i-p substrate-type µc-SiH thin-film solar cells. Measured layer thicknesses, interface geometries and optical data from the prototypes are used such that simulated and experimental spectral response and reflection of the solar cells can be directly compared. Furthermore, from the simulated three-dimensional electromagnetic field distributions, detailed absorption profiles were calculated. The three-dimensional absorption profiles allow for a layer specific evaluation of the parasitic losses in n-i-p substrate-type µc-SiH solar cells deposited on plasmonic reflection grating back contacts.

A three-dimensional numerical solver of Maxwell’s equations was used to study the interaction of electromagnetic waves and n-i-p substrate-type µc-SiH thin-film solar cells. The simulations were conducted with the commercially available program JCMsuite.21 This software is based on the finite element method and solves Maxwell’s equations on a prismatic grid in three dimensions. From the simulated three-dimensional electric field distributions, three-dimensional power loss spectra were calculated. The spectral response, or in other words the EQE of the solar cells was calculated assuming a perfect collection of the generated charge carriers in the intrinsic µc-SiH layer and a collection efficiency of 50% in the n-doped µc-SiH layer. In explicit, it is assumed that every absorbed photon in the intrinsic µc-SiH layer and 50% of the photons absorbed in the n-doped µc-SiH layer contribute to the photocurrent. Photons absorbed in any other layer do not contribute to the photocurrent.

The optical material properties of the dielectric layers in the solar cell are described with the dielectric function. The dielectric functions of the intrinsic, p-doped and n-doped µc-SiH as well as the front and rear ZnOAl were taken from experimental data assembled in the institute IEK-5 Photovoltaik (Forschungszentrum Jülich). For this reference set of data, different experimental methods are combined, including photothermal deflection spectroscopy and ellipsometry.

Two types of n-i-p substrate-type µc-SiH solar cells were investigated: (1) a flat solar cell and (2) a solar cell applying a plasmonic reflection grating back contact with a period of 500 nm. A schematic cross-section of the latter solar cell design is shown in Fig. 1. The geometrical data for the simulation are taken from scanning electron microscopy images of the solar cell cross-section (prepared by focused ion beam) as well as atomic force microscopy measurements of the interfaces in between different fabrication steps. Due to the non-conformal growth of the µc-SiH layers the nanostructure of the substrate is leveled and broadened significantly at the front side of the solar cell. Instead of protrusions of radii of 110 nm and height of 80 nm we obtain at the front side of the solar cell regular half-ellipsoidal structures of diameter of 300 nm and height of 35 nm. For the flat solar cell we assume perfectly flat interfaces. Throughout this study, the incident electromagnetic wave penetrates the geometries under study at normal incidence.

To provide an example of the simulated electric field distribution, the absolute electric field distribution is given in Fig. 2 for a solar cell applying a plasmonic reflection. The electric field is shown in a plane parallel and perpendicular to the polarization of the incident electromagnetic wave. For the plane parallel to the polarization of the incident light, the enhanced electric fields in the vicinity of the nanostructure indicate the LSPP resonance of the nanostructure. A detailed investigation of the localized plasmon polariton resonances apparent in those Ag nanostructures under study was provided in a previous study.19 For the plane perpendicular to the polarization of the incident electromagnetic wave this enhancement of the electric field is not apparent as the plasmonic resonance oscillates in plane with the exciting electric field of the incident electromagnetic wave.

Graphic Jump LocationF2 :

Absolute electric field distribution in the two square lattice symmetry planes of a n-i-p substrate-type solar cell applying a plasmonic reflection grating back contact (period of 500 nm). The data are shown in a plane parallel (a) and perpendicular (b) to the polarization of the incident electromagnetic wave (wavelength of 720 nm).

Electromagnetic Simulations of Flat µc-Si∶H Solar Cells

In Fig. 3(a) the simulated EQE data of a flat µc-SiH solar cell is compared to experimental EQE data. The data are shown for wavelengths from 300 to 1100 nm. A very good agreement between the experimental data and the simulated data was achieved for the EQE in the wavelength range from 300 to 550 nm. For longer wavelengths, due to the lower absorption in µc-SiH, incident light reaches the back contact and interferences appear in the EQE due to the flat solar cell layer stack. In the simulated data, only the spectral position of the interferences is comparable to the experimental EQE. The modulation depth of the interferences in the simulated EQE data exceeds strongly the modulation depth of the interferences in the experimentally measured EQE. There are three reasons for this deviation: First, the bandwidth of the EQE measurement setup used in this work is around 10 nm. Thus, the very steep modulations of bandwidth of similar size are smeared out in the measurements. Second, the thickness of the dielectric layers in the µc-SiH solar cell layer stack varies slightly due to inhomogeneity in the deposition processes. As the maximum spot diameter of the EQE measurement setup is around 3 mm a modulation of the layer thicknesses over the spot size needs to be considered when comparing simulated EQE data to experimental values. Third, due to a residual roughness of the flat ZnOAl substrate and a growth-induced roughness of the µc-SiH layer, the surface of the solar cell deposited on a flat substrate is not perfectly flat. The residual root mean square roughness in the 10 nm range reduces the modulation depth of the interference fringes in the EQE. One way to compensate for the deviation between the simulated perfectly flat solar cell and the experimental data on a nearly flat solar cell is to average the EQE data of the solar cell over a variation of thicknesses of the solar cell layers. For this reason, in Fig. 3(b), a simple moving average with a final resolution of 10 nm of three simulated EQE data of flat µc-SiH solar cells with i-layer thicknesses of 1082nm±25nm is compared to the experimental data. The averaged simulated EQE data show a very good agreement with measured EQE data over the entire wavelength spectrum.

Graphic Jump LocationF3 :

Simulated (red or blue line, open squares) and measured (gray line, filled circles) external quantum efficiency (EQE) of a n-i-p substrate-type µc-SiH solar cell deposited on a flat substrate. In (a) the EQE data of a single simulation is presented. In (b) the simple moving average with a final resolution of 10 nm of three simulations is given. The initial intrinsic layer thickness of 1082 nm is varied by ±25nm.

Electromagnetic Simulations of µc-Si∶H Solar Cells with Integrated Plasmonic Reflection Grating Back Contact

In Fig. 4 the simulated EQE data of a n-i-p substrate-type µc-SiH solar cell deposited on a plasmonic reflection grating back contact is compared to experimental data. For this configuration, the plasmonic reflection grating back contact is formed by half-ellipsoidal Ag nanostructures arranged in square lattice [see scanning electron microscopy image in Fig. 1(c)]. In Fig. 4(a) the EQE data of a single simulation at a fixed i-layer thickness of 1082 nm is shown. Similar to the simulated EQE data of the flat solar cell we obtain a very good agreement between simulation and experimental EQE data for wavelengths smaller than 550 nm. For longer wavelengths only the positions of the interferences observed in the measured EQE are reproduced reasonably in the simulations. Such interferences, similar to the interfaces observed in flat solar cells are also apparent for the solar cell deposited on the plasmonic reflection grating back contact as it applies a regular light-trapping structure.20 In contrast to the flat solar cell, the simulated EQE data of the solar cell applying a plasmonic reflection grating back contact also reveals very sharp resonances, which are attributed to the waveguide modes of the periodic solar cell design. In case of a plasmonic reflection grating back contact, the grating at the back contact allows the incident light to couple to the waveguide modes of the solar cell layer stack. However, as the bandwidth of these modes is very narrow (from 2 to 6 nm) they are not resolved in the measured EQE data. Thus, in order to compare simulations and experiment in Fig. 4(b), a simple moving average of three simulations as described in the previous section is shown. As a result, a very good fit between simulations and experimental results is obtained in the total wavelength range of interest. This agreement forms an excellent basis for future simulation-based optimizations of the light-trapping by plasmonic reflection grating back contacts.

Graphic Jump LocationF4 :

Simulated (red or blue line, open squares) and measured (black line, filled circles) external quantum efficiency (EQE) of a n-i-p substrate-type µc-SiH solar cell deposited on a plasmonic reflection grating back contact. In (a) the EQE data of a single simulation is presented. In (b) the simple moving average with a final resolution of 10 nm of three simulations is given. The initial intrinsic layer thickness of 1082 nm is varied by ±25nm.

Evaluation of Losses and Gains in Solar Cells Applying Flat and Periodic Reflection Grating Back Contacts

From the electromagnetic simulations of n-i-p substrate-type µc-SiH solar cells three-dimensional power loss profiles were calculated allowing for a layer-specific evaluation of the absorptance. In Fig. 5 this layer-specific absorptance of solar cells deposited on a flat substrate [Fig. 5(a)] and a plasmonic reflection grating [Fig. 5(b)] is shown for wavelengths from 500 to 1100 nm. In this wavelength range both solar cells have been found to differ in the EQE as only for wavelengths larger than 550 nm incident light reaches the back contact.20 For both solar cells the major part of the absorbed light is absorbed in the intrinsic µc-SiH layer and will contribute to the photocurrent of the solar cell. All of the incident light absorbed in the ZnOAl/Ag back contact, the p-doped µc-SiH and front ZnOAl layer and 50% of the light absorbed in the n-doped µc-SiH layer will not contribute to the photocurrent and is, therefore, considered as a parasitic absorption loss. For wavelengths up to 550 nm most of the parasitic absorption losses appear in the p-doped µc-SiH layer of the solar cells. For longer wavelengths the absorptance in the ZnOAl front contact, the n-doped µc-SiH layer and the back contact, consisting of the Ag layer and the back ZnOAl layer gains relevance.

Graphic Jump LocationF5 :

Simulated layer specific absorptance of a flat solar cell (a) and a solar cell deposited on a plasmonic reflection grating back contact (b).

As reported in the previous section the light-trapping effect found for the solar cells deposited on the plasmonic reflection grating back contact enhances the absorptance in the intrinsic µc-SiH layer. This enhancement is also shown in Fig. 5. It results in an increase in photocurrent from 17.7 to 21.0mA/cm2. Importantly, also the parasitic losses in the back contact and the n-doped µc-SiH layer increase strongly for the solar cell deposited on the plasmonic reflection grating back contact as shown in Fig. 5(b). For wavelengths longer than 750 nm, 33% of the light absorbed in the solar cell is absorbed by either the n-doped µc-SiH layer or the back contact. In particular, the parasitic losses in Ag increase by a factor of 4.3 when comparing the EQE data of the two solar cells presented in Fig. 5(a) and 5(b), respectively. Thus, the enhanced light-trapping effect found for the solar cells deposited on the plasmonic reflection grating comes at the cost of an enhanced parasitic absorption in the Ag layer, i.e., the LSPP resonances in the nanostructured Ag layer scatter incident light but also induce losses, leading to an enhanced absorption. In addition, due to the light-trapping effect, light is guided in the solar cell layer stack and will interact more often with a plasmonic reflection grating back contact, leading to a further increase of the absorptance in the Ag layer. Consequently, in order to improve the performance of the plasmonic reflection grating back contact it is important to increase the scattering-induced light-trapping and decrease the optical losses in the back contact. For further optimization of the plasmonic reflection grating back contact the enhanced absorptance in the Ag layer might become a limiting factor.

In this contribution, the interaction of incident light with µc-SiH solar cells with an integrated plasmonic reflection grating back contact is studied with three-dimensional electromagnetic simulations and measurements of the spectral response of prototypes. The investigated plasmonic reflection grating back contact consists of half-ellipsoidal Ag nanostructures arranged in square lattice at the back contact of a n-i-p substrate-type µc-SiH thin-film solar cell. The experimental results of the prototypes of these solar cells show significantly enhanced Jsc in comparison to flat solar cells and even a small enhancement of the Jsc in comparison to the conventional random texture light-trapping concept of thin-film silicon solar cells. A comparison of simulated and measured EQE data of the prototype solar cells shows an excellent agreement when taking into account experimental variations (e.g., in the thickness of the solar cell layers). In particular, the predictive power of the simulations is demonstrated, which is very useful for further optimizations of the solar cell design. From the simulated three-dimensional electromagnetic field distributions, detailed power loss profiles were calculated allowing for spatially resolved evaluations of parasitic losses inside the n-i-p substrate-type µc-SiH thin-film solar cells. It was shown that the enhanced light-trapping found for the solar cell deposited on the plasmonic reflection grating comes at the cost of an enhanced absorption in the Ag layer. Nevertheless, in the solar cells under study for wavelengths longer than 750 nm the EQE is low and reflection losses are dominant such that the enhanced absorptance in Ag is not affecting the solar cell performance. However, enhanced absorptance in the Ag layer might become a limiting factor for the further optimization of the plasmonic reflection grating back contact.

The authors thank K. Bittkau, U. Aeberhard, M. Meier, D. Michaelis, C. Waechter, V. Hagemann, and S. Burger for helpful discussions. The financial support from the German Federal Ministry of Education and Research under contract 03SF0354D is acknowledged.

Rech  B. et al., “Challenges in microcrystalline silicon based solar cell technology,” Thin Solid Films. 511–512, , 548 –555 (2006). CrossRef. 0040-6090 
Müller  J. et al., “TCO and light-trapping in silicon thin-film solar cells,” Sol. Energ.. 77, , 917 –930 (2004). CrossRef. 0038-092X 
Matsui  T. et al., “Influence of substrate texture on microstructure and photovoltaic performances of thin-film polycrystalline silicon solar cells,” J. Non-Cryst. Solids. 299–302, , 1152 –1156 (2002). CrossRef. 0022-3093 
Söderström  T. et al., “ZnO transparent conductive oxide for thin-film silicon solar cells,” Proc. SPIE. 7603, , 76030B  (2010). CrossRef. 0277-786X 
Wang  A., Zhao  J., Green  M. A., “24% efficient silicon solar cell,” Appl. Phys. Lett.. 57, , 602  (1990). CrossRef. 0003-6951 
Stiebig  H. et al., “The application of grating couplers in thin-film silicon solar cells,” Sol. Energ. Mater. Sol. Cell. 90, , 3031  (2006). CrossRef. 0927-0248 
Söderström  K. et al., “Photocurrent increase in n-i-p thin-film silicon solar cells by guided mode excitation via grating coupler,” Appl. Phys. Lett.. 96, , 213508  (2010). CrossRef. 0003-6951 
Atwate  H. A., Polman  A., “Plasmonics for improved photovoltaic devices,” Nat. Mat.. 9, , 205 –213 (2010). CrossRef. 1476-1122 
Hallermann  F. et al., “On the use of localized plasmon polaritons in solar cells,” Phys. Status Solidi A. 205, , 2844  (2008). CrossRef. 0031-8965 
Sai  H., Kondo  M., “Effect of self-orderly textured back reflectors on light-trapping in thin-film microcrystalline silicon solar cells,” J. Appl. Phys.. 105, , 094511  (2009). CrossRef. 0021-8979 
Kreibig  U., Vollmer  M., Optical Properties of Metal Clusters. ,  Springer-Verlag ,  Berlin  (1995).
Catchpole  K. B., Polman  A., “Plasmonic solar cells,” Appl. Phys. Lett.. 93, , 191113  (2008). CrossRef. 0003-6951 
Fahr  S., Rockstuhl  C., Lederer  F., “Photonic crystal intermediate reflector in micromorph tandem solar cells,” Appl. Phys. Lett.. 95, , 121105  (2009). CrossRef. 0003-6951 
Ferry  V. E. et al., “Light-trapping in ultrathin photovoltaic devices,” Opt. Express. 18, , 102  (2010). CrossRef. 1094-4087 
Ferry  V. E. et al., “Optimized spatial correlations for broadband light trapping nanopatterns in high rfficiency ultrathin film a-Si∶H solar cells,” Nanoletters. 11, , 4239 –4245 (2011). 1530-6984 CrossRef
Moulin  E. et al., “Improved light absorption in thin-film silicon solar cells by integration of silver nanoparticles,” J. Non-Cryst. Solids. 354, , 2488 –2491 (2008). CrossRef. 0022-3093 
Moulin  E. et al., “Thin-film silicon solar cells with integrated silver nanoparticles,” Thin Solid Films. 516, , 6813 –6817 (2008). CrossRef. 0040-6090 
Biswas  R., Xu  C., “Nano-crystalline silicon solar cell architecture with absorption at the classical 4n2 limit,” Opt. Express. 19, , A664 –A672 (2011). CrossRef. 1094-4087 
Paetzold  U. W. et al., “Design of nanostructured plasmonic back contacts for thin-film silicon solar cells,” Opt. Express. 19, , A1219 –A1230 (2011). CrossRef. 1094-4087 
Paetzold  U. W. et al., Appl. Phys. Lett.. 99, , 181105  (2011). CrossRef. 0003-6951 
Pomplun  J. et al., “Adaptive finite element method for simulation of optical nano structures,” Phys. Status Solidi B. 244, , 3419 –3434 (2007). CrossRef. 0370-1972 

Biographies and photographs of the authors are not available.

© 2012 Society of Photo-Optical Instrumentation Engineers

Citation

Ulrich W. Paetzold ; Etienne Moulin ; Bart E. Pieters ; U. Rau and R. Carius
"Optical simulations of microcrystalline silicon solar cells applying plasmonic reflection grating back contacts", J. Photon. Energy. 2(1), 027002 (Jun 11, 2012). ; http://dx.doi.org/10.1117/1.JPE.2.027002


Figures

Graphic Jump LocationF5 :

Simulated layer specific absorptance of a flat solar cell (a) and a solar cell deposited on a plasmonic reflection grating back contact (b).

Graphic Jump LocationF4 :

Simulated (red or blue line, open squares) and measured (black line, filled circles) external quantum efficiency (EQE) of a n-i-p substrate-type µc-SiH solar cell deposited on a plasmonic reflection grating back contact. In (a) the EQE data of a single simulation is presented. In (b) the simple moving average with a final resolution of 10 nm of three simulations is given. The initial intrinsic layer thickness of 1082 nm is varied by ±25nm.

Graphic Jump LocationF2 :

Absolute electric field distribution in the two square lattice symmetry planes of a n-i-p substrate-type solar cell applying a plasmonic reflection grating back contact (period of 500 nm). The data are shown in a plane parallel (a) and perpendicular (b) to the polarization of the incident electromagnetic wave (wavelength of 720 nm).

Graphic Jump LocationF1 :

(a) Schematic cross section of the n-i-p substrate-type solar cell deposited on a plasmonic reflection grating back contact. The three-dimensional layer stack of the front contact and reflection grating back contact is shown schematically in (b) and (c), respectively. (d) Scanning electron microscopy image of the nanostructured Ag surface at the back contact of the solar cell.

Graphic Jump LocationF3 :

Simulated (red or blue line, open squares) and measured (gray line, filled circles) external quantum efficiency (EQE) of a n-i-p substrate-type µc-SiH solar cell deposited on a flat substrate. In (a) the EQE data of a single simulation is presented. In (b) the simple moving average with a final resolution of 10 nm of three simulations is given. The initial intrinsic layer thickness of 1082 nm is varied by ±25nm.

Tables

Table Grahic Jump Location
Table 1Short-circuit current densities Jsc of n-i-p substrate-type μc-SiH thin-film solar cells deposited on three different types of substrates: (i) a flat back contact, (ii) a random texture back contact, and (iii) a plasmonic reflection grating back contact of 500 nm period.20

References

Rech  B. et al., “Challenges in microcrystalline silicon based solar cell technology,” Thin Solid Films. 511–512, , 548 –555 (2006). CrossRef. 0040-6090 
Müller  J. et al., “TCO and light-trapping in silicon thin-film solar cells,” Sol. Energ.. 77, , 917 –930 (2004). CrossRef. 0038-092X 
Matsui  T. et al., “Influence of substrate texture on microstructure and photovoltaic performances of thin-film polycrystalline silicon solar cells,” J. Non-Cryst. Solids. 299–302, , 1152 –1156 (2002). CrossRef. 0022-3093 
Söderström  T. et al., “ZnO transparent conductive oxide for thin-film silicon solar cells,” Proc. SPIE. 7603, , 76030B  (2010). CrossRef. 0277-786X 
Wang  A., Zhao  J., Green  M. A., “24% efficient silicon solar cell,” Appl. Phys. Lett.. 57, , 602  (1990). CrossRef. 0003-6951 
Stiebig  H. et al., “The application of grating couplers in thin-film silicon solar cells,” Sol. Energ. Mater. Sol. Cell. 90, , 3031  (2006). CrossRef. 0927-0248 
Söderström  K. et al., “Photocurrent increase in n-i-p thin-film silicon solar cells by guided mode excitation via grating coupler,” Appl. Phys. Lett.. 96, , 213508  (2010). CrossRef. 0003-6951 
Atwate  H. A., Polman  A., “Plasmonics for improved photovoltaic devices,” Nat. Mat.. 9, , 205 –213 (2010). CrossRef. 1476-1122 
Hallermann  F. et al., “On the use of localized plasmon polaritons in solar cells,” Phys. Status Solidi A. 205, , 2844  (2008). CrossRef. 0031-8965 
Sai  H., Kondo  M., “Effect of self-orderly textured back reflectors on light-trapping in thin-film microcrystalline silicon solar cells,” J. Appl. Phys.. 105, , 094511  (2009). CrossRef. 0021-8979 
Kreibig  U., Vollmer  M., Optical Properties of Metal Clusters. ,  Springer-Verlag ,  Berlin  (1995).
Catchpole  K. B., Polman  A., “Plasmonic solar cells,” Appl. Phys. Lett.. 93, , 191113  (2008). CrossRef. 0003-6951 
Fahr  S., Rockstuhl  C., Lederer  F., “Photonic crystal intermediate reflector in micromorph tandem solar cells,” Appl. Phys. Lett.. 95, , 121105  (2009). CrossRef. 0003-6951 
Ferry  V. E. et al., “Light-trapping in ultrathin photovoltaic devices,” Opt. Express. 18, , 102  (2010). CrossRef. 1094-4087 
Ferry  V. E. et al., “Optimized spatial correlations for broadband light trapping nanopatterns in high rfficiency ultrathin film a-Si∶H solar cells,” Nanoletters. 11, , 4239 –4245 (2011). 1530-6984 CrossRef
Moulin  E. et al., “Improved light absorption in thin-film silicon solar cells by integration of silver nanoparticles,” J. Non-Cryst. Solids. 354, , 2488 –2491 (2008). CrossRef. 0022-3093 
Moulin  E. et al., “Thin-film silicon solar cells with integrated silver nanoparticles,” Thin Solid Films. 516, , 6813 –6817 (2008). CrossRef. 0040-6090 
Biswas  R., Xu  C., “Nano-crystalline silicon solar cell architecture with absorption at the classical 4n2 limit,” Opt. Express. 19, , A664 –A672 (2011). CrossRef. 1094-4087 
Paetzold  U. W. et al., “Design of nanostructured plasmonic back contacts for thin-film silicon solar cells,” Opt. Express. 19, , A1219 –A1230 (2011). CrossRef. 1094-4087 
Paetzold  U. W. et al., Appl. Phys. Lett.. 99, , 181105  (2011). CrossRef. 0003-6951 
Pomplun  J. et al., “Adaptive finite element method for simulation of optical nano structures,” Phys. Status Solidi B. 244, , 3419 –3434 (2007). CrossRef. 0370-1972 

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Book Chapters

Topic Collections

PubMed Articles
Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Article
Sign in or Create a personal account to Buy this article ($20 for members, $25 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.