Simulated 34% Efficient 2T Monolithic CsPbI/Si Tandem Solar Cells: The Effect of Tailoring Nonradiative Voltage Losses.

The power conversion efficiency (PCE) of single-junction perovskite solar cells has increased dramatically since their inception. In cesium lead iodide perovskite/silicon (CsPbI/Si) tandem solar cells (TSCs), Shockley-Read-Hall (SRH), radiative, and thermodynamic recombination losses are the primary source of voltage loss and govern the PCE of the device. Although the Shockley-Queisser (SQ) limit for power conversion efficiency of CsPbI/Si TSC is ∼40%, realizing this is difficult due to recombination losses and thermal instability of CsPbI. The proper choice of material and a suitable device structure can improve these. In this study, we used a thermally stable phase of CsPbI and optimize the SRH recombination loss in a CsPbI-based standalone inverted architecture solar cell device with configuration FTO/SnO/C/CsPbI/2F (4-(7-(4-bis-(4-methylphenyl) amino)-2,5-difluorophenyl) benzol [] [1,2,5] thiadiazol-4-yl) benzoic acid). An optimized standalone CsPbI-based solar cell exhibits outstanding performance with an open-circuit voltage of 1219.0 mV, short-circuit current density of 21.28 mA/cm, fill factor of 81.99%, and PCE of 21.27%. Further, we have integrated this optimized CsPbI-based standalone solar cell over a highly efficient silicon (Si) heterojunction solar cell, i.e., IZO/-nc-SiO /-a-Si:H/-c-Si/-a-Si:H/-nc-Si:H, in series to model the CsPbI/Si two-terminal (2T) TSC in current-matching conditions utilizing filtered spectrum. In an optimized condition, the PCEs of 2T monolithic and 4T mechanically stacked TSCs are 34.05 and 33.89%, respectively. All the simulation results are well corroborated with the experimental findings, providing a robust validation of the proposed simulation models and inspiring hope for future highly efficient device fabrication.