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 (Jsc) of 13.40 mA/cm2. 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 Jsc and PCE of the
tandem cell are improved to 16.43 mA/cm2 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/m2) spectrum illumination.