Blue organic long-persistent luminescence via upconversion from charge-transfer to locally excited singlet state

Blue organic long-persistent luminescence via upconversion from charge-transfer to locally excited singlet state

Blog Article

Abstract Long-persistent luminescence (LPL) materials have applications from safety signage to bioimaging; however, existing organic LPL (OLPL) systems do not align with human scotopic vision, which is sensitive to blue light.We present a strategy to blueshift the emissions in binary OLPL systems by upconverting the charge-transfer (CT) to a locally excited (LE) singlet state.Through rigorous steady-state and beetroot birkenstock time-resolved photoluminescence spectroscopy and wavelength-resolved thermoluminescence measurements, we provide the direct experimental evidence for this upconversion in OLPL systems featuring small energy offsets between the lowest-energy CT and LE singlet states.These systems exhibited strong room temperature LPL, particularly when extrinsic electron traps are added.Importantly, the developed OLPL system achieved Class A (ISO 17398) LPL, matching well with human scotopic vision.

The findings not only elucidate the role of small energy offsets in modulating LPL but also provide potential 3 piece horse wall art avenues for enhancing the efficiency and applicability of OLPL materials.