Germanium doping effect on the photoelectronic performance of alternating cations in the interlayer space GA(MA)3(Pb1−xGex)3I10

Abstract

The perovskite solar cells (PSCs), based on the two-dimensional (2D) perovskites stabilized by alternating cations in the interlayer space (ACI), have recently received remarkable attention due to the impressive power conversion efficiency (PCE) exceeding 18%. Pursuing ways to alleviate the toxicity of lead has emerged as a hot topic in the community of PSCs. Herein, we investigate potential alternatives to ACI 2D GA(MA)₃Pb₃I₁₀ perovskites by replacing lead with germanium (Ge) of various compositions using first-principles calculations. We demonstrate the pivotal role of Ge doping in finely adjusting the bandgap, enhancing broad-emission features, and improving Stokes shifts and Huang–Rhys factors. Fabricating GA(MA)₃(Pb_1−xGe_x)₃I₁₀ candidates, especially within the range from 8.3% to 50% Ge content, demonstrate minor energy level offsets at the conduction band minimum adjacent to the electron transport layer. Significantly, GA(MA)₃(Pb_0.083Ge_0.917)₃I₁₀ exhibits the strongest carrier transport ability, with the highest electron mobility of 2492.9 cm² V⁻¹ s⁻¹. Moreover, compositions ranging from 8.3% to 75% exhibit improved optical-electronic properties and photovoltaic response compared to GA(MA)₃Pb₃I₁₀, with GA(MA)₃(Pb_0.75Ge_0.25)₃I₁₀ and GA(MA)₃(Pb_0.667Ge_0.333)₃I₁₀ standing out with PCE values exceeding 22%, positioning them as promising photo-absorber candidates for photovoltaic applications. Our findings provide valuable insights into the significant role of Ge doping in shaping the distinctive photoelectronic properties of ACI 2D GA(MA)₃(Pb_1−xGe_x)₃I₁₀ perovskites, thereby paving the way for innovative approaches to advance their applications in optoelectronics.