Numerical analysis of ultra-thin CdTe solar cell: An optimized design of polymer materials as HTLs

The incorporation of PEDOT:PSS and Spiro-OMeTAD as Hole Transport Layer (HTL) in CdTe solar cells is evaluated by SCAPS considering FTO/CdS/CdTe/HTL/Cu:Au solar cell structure. First, experimental data of CdS/CdTe solar cells without HTL is theoretically validated, demonstrating good agreement between theoretical and experimental information. It is shown that improvements in open-circuit voltage to values higher than 800 mV with efficiencies of 9.8 % are achieved by incorporating HTLs. In addition, we found that very thin layers of 220 nm width are beneficial to the device, reducing significantly Cd amount, and being aligned with the environmental sustainability goals. The optimization of the physical properties of HTL and CdTe materials is analyzed, finding a conversion efficiency of about 23 %.