Simultaneous Enhanced Device Efficiency and Color Neutrality in Semitransparent Organic Photovoltaics Employing a Synergy of Ternary Strategy and Optical Engineering

Power conversion efficiency (PCE) and color rendering index (CRI) are two important parameters for realizing the potential application of semitransparent organic photovoltaics (ST-OPVs) into the field of building-integrated photovoltaics (BIPVs). Herein, to extend the PCE limit while showing desirable neutral-colored perception, formally in a trade-off relationship, of ST-OPVs, new ternary photoactive layers composed of polymer donor PM6-Ir1, non-fullerene acceptor BTP-eC9, and fullerene acceptor PC71BM as the third component are employed, which are effective to improve opaque device efficiency while modulating CRI in relevant ternary blends. Furthermore, multifunctional ST-OPVs are realized via simultaneously optimizing the content of PC71BM in acceptors and employing a simple photonic reflector, leading to not only excellent neutral color perception with a CRI of 96.5 but also a PCE of 14.09% with an average visible transmittance higher than 20%. Vivid backgrounds can be clearly seen through the 1-DBR-based ternary ST-OPVs. Overall, these results represent the best-performing multifunctional ST-OPVs, and this synergistic effect can pave the road for ST-OPVs as promising BIPVs of high device performance and good color neutrality.

Automated summary

The study demonstrates that using new ternary photoactive layers can improve both the power conversion efficiency and color rendering index of semitransparent organic photovoltaics, leading to excellent neutral color perception. In addition, multifunctional semitransparent organic photovoltaics can be achieved by optimizing the content of PC71BM in the acceptors and using a photonic reflector, resulting in high device performance and good color neutrality.