Impact of Self‐Absorption and Cavity Effects on the Electroluminescence Spectra of Thin‐Film Solar Cells

Abstract

Thin‐film organic and perovskite solar cells have seen tremendous advances in recent years. A common technique to characterize the low‐energy states in these solar cells is electroluminescence spectroscopy. Stemming from their thin film nature, however, the outcoupled electroluminescence spectra of these devices are affected by cavity effects and self‐absorption. Herein, a modeling approach is developed taking into account self‐absorption, cavity effects, and a nonhomogeneous emission profile, to correct the outcoupled spectrum, thereby yielding the intrinsically emitted spectrum. The modeling approach is then employed to structurally investigate the impact of these effects for a variety of active layer thicknesses, complex refractive indices, device structures, and emission profiles. The data presented uncover trends and provide guidelines that enable gauging the impact of self‐absorption and cavity effects on the electroluminescence spectra of a large set of thin‐film devices.