Band Alignment for Rectification and Tunneling Effects in Al2O3 Atomic-Layer-Deposited on Back Contact for CdTe Solar Cell

The present work intends to explain why ultrathin Al2O3 atomic-layer-deposited (ALD) on the back contact with rectification and tunneling effects can significantly improve the performance of CdTe solar cells in our previous work [ Liang , J. ; et al. Appl. Phys. Lett. 2015 , 107 , 013907 ]. Herein, we further study the mechanism through establishing the interfacial energy band diagram configuration of the ALD Al2O3/CuxTe by experiment of X-ray photoelectron spectroscopy and first-principles calculations and conclude to find the band alignment with optimized layer thickness (about 1 nm ALD Al2O3) as the key factor for rectification and tunneling effects.