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

Tin-based halide perovskites (Sn-HPs) are emerging aspromising alternatives to lead-based perovskites in solar cells due to theirreduced toxicity and advantageous optoelectronic properties. However, Sn-HPsface significant challenges such as rapid crystallization, high defect density,and limited stability. This study introducesdiethyl-methyl-octadecanoyloxymethyl-ammonium iodide (DMOAI) as an interfaciallayer between poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS) and Sn-HP, aiming to mitigate these issues. DMOAI was observed tointeract with the PEDOT:PSS surface through its longchain molecules,coordinating with the Sn-HP lattice via C–N and C=O groups. This interaction modulatedthe surface energy of PEDOT:PSS, leading to controlled crystallization, reducedstrain, and improved crystallinity in the Sn-HP film. Consequently, the filmdisplayed enhanced coverage and a reduction in defect states, contributing tolower trap-assisted recombination and optimized energy level alignment forcharge transfer. As a result, the power conversion efficiency (PCE) of Sn-HPsolar cells increased from 10.42% to 13.39%, alongside improved operationalstability, with 85% of initial PCE retained after 2500 hours in an N₂ atmosphere. These findings highlight the potential of DMOAI as amultifunctional interfacial modifier for enhancing both performance andstability in Sn-HPSCs.