Opto-Electro-Thermal Loss Mechanisms and Optimization Design in Organic Solar Cells

Organic solar cells (OSCs) have garnered extensive attention due to their advantage of low cost and lightweight properties. However, owing to the complex interplay between excitons and charge carriers, the intrinsic energy loss pathways and performance-limiting factors in OSCs remain poorly understood. Herein, we established a comprehensive opto-electro-thermal (OET) model to quantify the exciton- and carrier-related thermodynamic loss mechanisms in organic photovoltaics, and identified seven inherent energy loss channels in OSCs. To identify the key bottlenecks limiting device performance, we further systematically explored the influences of temperature and key electrical parameters on device performance. The results reveal that operating temperature and carrier mobility impose opposite impacts on exciton dissociation and carrier recombination behaviors, and balancing these two loss types enables optimized OSC performance. Guided by these insights, we experimentally fabricated BHJ and LBL-type OSCs achieving a power conversion efficiency (PCE) of 19.7% and 19.9%, respectively. Furthermore, our results demonstrate that a PCE exceeding 22.2% can be expected for OSCs through the integration of rational material design and working temperature management. This study is critical for an in-depth understanding of OET-coupled physics in exciton- and carrier-mixed devices and provides a theoretical guide for the design of high-performance OSCs.