Experimental and computational insights into optimizing polymer solar cell operational parameters

This study explores the impact of active layer (AL) thickness, annealing temperatures(ATs), and interfacial materials on the performance of polymer solar cells (PSCs) based on P3HT: PCBM. AL thickness was tuned by varying spin speeds (1000–5000 rpm), with devices D1K and D4K achieving PCEs of 2.37 % and 2.17 % after thermal annealing at 130 °C. Increasing the AT to 180 °C further enhanced device efficiency. The influence of interfacial layers LiF and Ca on PSC performance and thermal stability was also investigated. Ca/Al-based devices outperformed others at lower temperatures but degraded at higher temperatures, while LiF/Al-based devices showed reduced PCE beyond ∼110 °C. To complement experiments, simulations using drift-diffusion, exciton-diffusion, and transfer-matrix models(TMM) were performed. These provided insights into photon distribution, absorption, and carrier generation, supporting the experimental outcomes. The study offers a comprehensive understanding of the interplay between device architecture and thermal treatment in optimizing PSC performance.