High-efficiency amorphous silicon solar cells with ZnO as front contact

B-doped ZnO films deposited by the photo-induced metalorganic chemical vapo r deposition (photo-MOCVD) method were applied to p-i-n single junction amo rphous silicon (a-Si) solar cells as front contacts. The thickness and the doping level of the p-layer were optimized in order to increase the open-ci rcuit voltage (V-oc) of the fabricated a-Si solar cells. As a result, a sta bilized conversion efficiency of 8.7% (V-oc: 0.926 V, J(sc): 14.6 mA/cm(2), FF: 0.646) was achieved under AM 1.5 (100 mW/cm(2)) illumination. Furtherm ore, the electrical properties of ZnO films were improved by employing an a tomic layer deposition (ALD) technique instead of the conventional MOCVD me thod, and a lower resistivity of 5 x 10(-4) Omega cm was achieved. It was a lso found that the stability of the electrical properties of ZnO films was improved by the ALD technique. The performance of the a-Si solar cells was further improved by applying the obtained high-quality ZnO films.