Practically Viable Approach to Efficient and Reliable Semitransparent Flexible Organic Solar Cells: Face‐Seal Encapsulation Embedded with Tailored Color‐Control Functionality

Abstract

The success of semitransparent organic solar cells (ST‐OSCs) depends heavily on whether they can achieve high efficiency while meeting the conditions for high transmittance or target apparent color. Herein, a device architecture for ST‐OSCs that achieves both enhanced efficiency and controlled apparent color or high transmittance is proposed, while providing protection from ambient air. In the proposed scheme, cells are encapsulated by a barrier foil embedded with a color‐controlling dielectric mirror (CCDM) structure, which is tailored for selective reflection at the targeted spectral band and transmission in the other spectral band. This approach effectively enhances the photocurrent with little compromise in transmittance, yet it allows control of the color of ST‐OSCs. Preparing these CCDMs independently of cell fabrication, the best material composition is utilized without damaging the underlying layers. With the proposed approach, ST‐OSCs with an efficiency of 8.30% and luminous transmittance over 30.4% are demonstrated. Furthermore, by setting ST‐OSCs in the neutral plane utilizing face‐seal encapsulation geometry, it is shown that these devices can maintain 98% of the initial efficiency even after 2000 cycles of repeated bending at a strain of 0.5%. Moreover, they can maintain initial efficiency very well in a highly damp condition for 120 h.