Imaging the Effect of CdSe Window Layers in CdTe Photovoltaics

Here we quantify and spatially resolve the carrier collection enhancement of CdSe window layers in CdTe photovoltaic devices by scanning photocurrent microscopy. We compare the photogenerated current of CdTe solar cells with both CdS and CdSe window layers. Our results show that, despite notable spatial variation in current in both cases, the device with the CdSe window layer outperforms the CdS one, in agreement with macroscopic analysis previously performed. The external quantum efficiency (EQE) enhancement occurs near the band edge of CdTe.