Investigation of Polymer/Si Thin Film Tandem Solar Cell Using TCAD Numerical Simulation

The current study introduces a two-terminal (2T) thin-film tandem solar cell (TSC) comprised of a polymer-based top sub cell and a thin crystalline silicon (c-Si) bottom sub cell. The photoactive layer of the top sub cell is a blend of PDTBTBz-2F as a polymer donor and PC71BM as a fullerene acceptor. Initially, a calibration of the two sub cells is carried out against experimental studies, providing a power conversion efficiency (PCE) of 9.88% for the top sub cell and 14.26% for the bottom sub cell. Upon incorporating both sub cells in a polymer/Si TSC, the resulting cell shows a PCE of 20.45% and a short circuit current density (J(sc)) of 13.40 mA/cm(2). Then, we optimize the tandem performance by controlling the valence band offset (VBO) of the polymer top cell. Furthermore, we investigate the impact of varying the top absorber defect density and the thicknesses of both absorber layers in an attempt to obtain the maximum obtainable PCE. After optimizing the tandem cell and at the designed current matching condition, the J(sc) and PCE of the tandem cell are improved to 16.43 mA/cm(2) and 28.41%, respectively. Based on this TCAD simulation study, a tandem configuration established from an all thin-film model may be feasible for wearable electronics applications. All simulations utilize the Silvaco Atlas package where the cells are subjected to standard one Sun (AM1.5G, 1000 W/m(2)) spectrum illumination.

Automated summary

This study presents a two-terminal thin-film tandem solar cell composed of a polymer-based top sub cell and a thin crystalline silicon bottom sub cell. Through calibration against experimental studies, the power conversion efficiency (PCE) of the top sub cell is 9.88% and the PCE of the bottom sub cell is 14.26%. When both sub cells are incorporated into the polymer/Si tandem solar cell, the resulting cell exhibits a PCE of 20.45%. Further optimization of the tandem performance improves the short circuit current density (J(sc)) and PCE to 16.43 mA/cm(2) and 28.41% respectively. Based on TCAD simulation, this all thin-film tandem configuration is feasible for wearable electronics applications.