Intrinsic ZnO (i-ZnO) thin films were deposited on glass substrates by radio-frequency magnetron sputtering for exploring the effects of the deposition conditions. These films were optically, electrically, and structurally characterized. Results showed that the properties of i-ZnO thin films changed with the changing of deposition conditions. These i-ZnO films were also integrated into (CIGS) solar cells. It was found that the incorporation of an i-ZnO layer in CIGS solar cells led to a significant improvement of homogeneity and efficiency of CIGS solar cells. An increment of 1.71% was gained in the average cell efficiency through adjusting the deposition conditions of i-ZnO layers. Detailed analysis showed that there was no improvement in cell efficiency under the deposition conditions favorable for growing the i-ZnO films. These results indicate that there should be a balance among the optimized performance of each layer deposited for high quality multi-layer devices.