Simulation Study for Nb-Doped MoS2 Layer in CZTS-Based Solar Cells: Assessment of Challenges

Abstract

The unintentional formation of a $$ layer as a reaction product between the copper zinc tin sulfide (CZTS) thin film and the Mo back contact reduces cell efficiency due to high sheet resistance and carrier recombination. To limit the formation of $$, an intentionally grown p-type Nb-doped $$ layer can serve as an effective hole transport layer. This study presents a detailed study and calculations for CZTS/Mo-based solar cells, providing guidelines for calibration. Optimizing cell efficiency is influenced by various interconnected factors in Nb-doped $$. While a high carrier concentration in Nb-doped $$ is assumed to enhance efficiency, other parameters such as band state, optical absorption, and carrier mobility also play crucial roles and can limit cell performance. This simulation study evaluated the effect of Nb-doped $$ layers with different carrier concentrations to determine the optimal conditions for this p-type layer. This work reveals that a very thin layer (13 nm) of Nb-doped p-type $$ can achieve a maximum efficiency of 11.34% (with $$ = 1.5$$ $$) and that for an Nb-doped p-type 62 nm $$ is 15.82 % (with $$ = 4.03$$ $$).