Enhanced tin halide perovskite solar cells via crystal growth control using a multifunctional interfacial modifier

Abstract

Tin-based halide perovskites (Sn-HPs) are emerging as promising alternatives to lead-based perovskites in solar cells due to their reduced toxicity and advantageous optoelectronic properties. However, Sn-HPs face significant challenges such as rapid crystallization, high defect density, and limited stability. This study introduces diethyl-methyl-octadecanoyloxymethyl-ammonium iodide (DMOAI) as an interfacial layer between poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and Sn-HP, aiming to mitigate these issues. DMOAI was observed to interact with the PEDOT:PSS surface through its long-chain molecules, coordinating with the Sn-HP lattice via C–N and CO groups. This interaction modulated the surface energy of PEDOT:PSS, leading to controlled crystallization, reduced strain, and improved crystallinity in the Sn-HP film. Consequently, the film displayed enhanced coverage and a reduction in defect states, contributing to lower trap-assisted recombination and optimized energy level alignment for charge transfer. As a result, the power conversion efficiency (PCE) of Sn-HP solar cells increased from 10.42% to 13.39%, alongside improved operational stability, with 85% of initial PCE retained after 2500 hours in an N₂ atmosphere. These findings highlight the potential of DMOAI as a multifunctional interfacial modifier for enhancing both performance and stability in Sn-HPSCs.