High rate, solution grown ZnO for a-Si:H based solar cells

We have developed a solution-grown ZnO process, and scaled it up to roll-to-roll (RTR) pilot production. We have fabricated Ag/ZnO based back reflector on stainless steel web using the solution grown ZnO process. The process has been optimized to attain good device characteristics on thin film, amorphous silicon alloy (a-Si:H) based multijunction solar cells. The surface morphology and crystallographic structure of the ZnO films were investigated. We found that for our optimized film with ~2 μm thickness, the grain size is about 1 μm. While the as-deposited film shows random crystal orientation, we developed a post-deposition treatment that effectively transforms the randomly orientated film into <;00L>; preferred orientation, that provides the best solar cell performance. The performance of solar cells made with Ag/ZnO back reflectors prepared using the solution-grown ZnO films is similar to solar cells having Ag/ZnO back reflectors made with sputtered ZnO films.