Solution-processed doping in CdTe thin film solar cells

Cadmium Telluride (CdTe) is one of the leading photovoltaic (PV) technologies in the world with a world record ~ 22.1%. With a bandgap of 1.45eV and a high absorption coefficient, the theoretical power conversion efficiency limit of 32% is limited by recombination and high resistivities in CdTe devices. Doping CdTe is a necessary way to improve device performance. In this work, it is demonstrated that a cost-effective solution-processed Group I and Group V doping in CdTe thin film solar cells allows for efficiency increases and stability improvement in CdTe devices. By varying the doping concentration, activation annealing temperatures, and deposition parameters, the root cause for the increased power conversion efficiency was investigated. Group I and Group V dopants showed smoother films indicating less resistance through the back contact leading to an increase in power conversion efficiencies.