High‐Performance Photoabsorber Based on 2D Perovskites with Alternating Cations in the Interlayer Space: GA(MA)₃M₃I₁₀

2D perovskites stabilized by alternating cations in the interlayer space (ACI) GA(MA) 3 Pb 3 I 10 perovskite have achieved a power conversion efficiency (PCE) of exceeding 18%. However, the potential leakage of broken cells with the usage of lead is still an environment problem. Thus, developing recycling end‐of‐life products via cost‐effective and environmentally friendly strategies is the current mainstream trend for perovskite solar cells. In this study, potential lead‐free alternatives to ACI 2D GA(MA) 3 M 3 I 10 perovskites with high optoelectronic and photovoltaic performance by replacing lead with metals such as Cd, Cu, Ge, Ni, Sn, Zn, Ca, Si, Fe, Mg, Sr, Ba, and Pd using first‐principles calculations are explored. The findings reveal that Cu, Zn, and Mg can finely tune the bandgap of GA(MA) 3 M 3 I 10 within the optimum range (0.9–2.3 eV) required for photovoltaic applications. GA(MA) 3 Cu 3 I 10 exhibits the strongest carrier transport ability, with the highest carrier mobility of 479.7 cm 2 V −1 s −1 . GA(MA) 3 Mg 3 I 10 demonstrates the highest PCE of 23.6%, positioning itself as a promising photoabsorber candidate for photovoltaic applications. Findings not only contribute to the design of environmentally friendly, high‐efficiency ACI 2D perovskites, but also unveil a mechanism that is not experimentally detected.