All-sputtered CdTe/CdS thin film solar cells with indium doped highly resistive absorber layer

The performance of CdTe-based thin film solar cells is dependent on intrinsic crystal properties such as carrier concentration, mobility, life time and resistivity. Improving crystal quality, in particular for photovoltaic energy conversion purposes, will lead to improvements in cell efficiency. Investigating the best initial CdTe material quality for conversion efficiency and cost efficiency is important to the scientific community as a whole. As a part of our systematic investigation, CdTe crystals doped with indium were grown using the vertical Bridgman method and a sputtering target of 3" is prepared. The resistivity of the bulk crystal was measured at ~10⁹ Ω.cm. Thin film solar cells were fabricated using standard superstrate configuration using Pilkington TEC 10 soda lime glasses for substrate. The structure of the layers were glass/SnO2:F/CdS/CdTe/Cu/Au. The fabricated solar cells were found to have small shunt resistance and larger series resistance. The efficiencies varied from near zero percent to 5%.