Sterically protected π-electron systems for efficient solid-state photon upconversion.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42336830.
- Also identified by DOI 10.1038/s41467-026-73898-0 and PMC identifier 13291331.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
A solid-state visible-to-ultraviolet triplet-triplet annihilation-based photon upconversion system driven by low-intensity light at sunlight levels is developed. Realizing such a solid-state photon upconversion system has been challenging because it is difficult to achieve high fluorescence quantum yield and fast triplet exciton diffusion simultaneously, which requires methodologies to precisely control interactions among chromophores and suppress quenching of both singlet and triplet excited states. Here, we report that a group of dihydroindeno[2,1-a]indene derivatives functionalized with alkyl chains above and below the π-plane satisfies all these requirements. Among three derivatives investigated, we identify the optimal emitter structure that exhibits the highest photon upconversion quantum yield in both solution and crystalline states. The solid-state system is less affected by crystalline defects, exhibiting high photoluminescence quantum yield, long triplet lifetime, and fast triplet diffusion, with an absolute photon upconversion quantum yield of 1.9% and a low threshold excitation intensity of 1.2 mW cm<sup>-2</sup>.