Intrinsic light reflection of conjugated films towards high-performance organic solar cells.

Abstract

In organic solar cells (OSCs), which represent a quintessential application system for organic conjugated films, the intrinsic light reflection of these films significantly influences the optical performance of the devices through the Fabry-Pérot micro-cavity effect. However, this phenomenon has not been comprehensively investigated. This study demonstrates that the film's intrinsic reflection arises from the light-matter interaction, which is mainly governed by the polarizability of delocalized electron cloud and the orientation of the conjugated backbone. Furthermore, the multi-level interference within the OSC micro-cavity leads to a dependence of both the reflection properties and the short-circuit current density (J_SC) on the active layer thickness. Based on these insights, a strategy for synergistic optimization of device performance through precise tailoring of optical constants and the micro-cavity structure is proposed. By systematically analyzing the intrinsic reflection behavior of organic conjugated films, this study enhances the understanding of the role reflection plays in the performance of photovoltaic devices and provides theoretical support for further optical optimization of organic photovoltaics.