Absorption bandwidth broadening of photon upconversion solid-solution organic crystals by co-dissolution of multiple sensitizers

Abstract

Abstract Photon upconversion (UC) enhances the utilization efficiency of solar energy. However, UC materials generally exhibit a narrow optical absorption bandwidth of the sensitizing molecules that create excited triplet states, including the case of solid-state UC materials. Here, we demonstrate the concept of simultaneous dissolution of multiple sensitizers into crystals of fluorescent molecules to broaden the absorption bandwidth, by using an example of combining two sensitizing porphyrins. Consequently, we appreciably enhanced the UC emission intensity under simulated sunlight. In the air, the developed solid-solution crystals exhibited excellent photostability over 50 h and a low excitation threshold of <1-Sun intensity.