The impact of Al2O3 back interface layer on low-temperature growth of ultrathin Cu(In,Ga)Se2 solar cells

Abstract:

With reducing the absorber layer thickness and processing temperature, the recombination at the back interface is severe, which both can result in the decrease of open-circuit voltage and fill factor. In this paper, we prepare Al2O3 by atomic layer deposition (ALD), and investigate the effect of its thickness on the performance of Cu(In,Ga)Se2 (CIGS) solar cell. The device recombination activation energy (EA) is increased from 1.04 eV to 1.11 eV when the thickness of Al2O3 is varied from 0 nm to 1 nm, and the height of back barrier is decreased from 48.54 meV to 38.05 meV. An efficiency of 11.57 % is achieved with 0.88-μm-thick CIGS absorber layer.