Green to blue photon upconversion in solid-state using anthracene and naphthalene diimide derivatives

Conventional photon upconversion (PUC) methods using intersystem crossing suffer from low efficiency of incident light utilization due to lowering light absorption to avoid suppression of triplet exciton deactivation by sensitizer aggregation. In this study, to overcome the difficulty, a combination of donor and acceptor materials was investigated to develop a blue PUC that relies on triplet formation by charge separation and recombination at the solid-state interface. An anthracene derivative was used for the donor and naphthalene diimide with visible light absorption was designed and synthesized for the acceptor. The key design principle of the acceptor material was controlling the energy level to proceed with charge separation and recombination emission at the interface with the anthracene. Using this study as a strategy for material selection opens the possibility of achieving solid-state PUC that exhibits a variety of emission wavelengths.