Comparative SCAPS-1D simulation of lead-based and lead-free 2D perovskite absorbers for high-efficiency solar cells

In recent studies, with the benefit of a highly stable quasi 2D Dion-Jacobson (DJ) phase, lead-iodide perovskite PeDAMA4Pb5I16 holds great potential to be employed in solar cells. The DJ structure is beneficial as it decreases van der Waals gaps between layers, enhancing stability. Though they are lead-based, they tend to have a wider bandgap, limiting light absorption and behaving more as an interfacial layer for defect passivation and CBO tuning. Thus, to overcome this drawback, the lead-free 2D perovskite material Cs2GeI2Br2 can provide a lower bandgap for improved absorption and enhanced photocurrent. Firstly, two structures have been simulated, both consisting of a single absorbent layer, PeDAMA4Pb5I16 and Cs2GeI2Br2, respectively. The latter one exhibited good performance in optoelectronic parameters such as J-V and QE, simulated with SCAPS-1D software. The outcomes obtained by optimizing the lead-based structure are a Power conversion efficiency (PCE) of 25.20% and a JSC of 18.25 mA/cm2. Whereas, after optimizing the lead-free structure, the achieved JSC is 27.10 mA/cm2, and PCE increased to 30.30%.