The statistical probability factor in triplet mediated photon upconversion: a case study with perylene
Journal article, 2023

Triplet-triplet annihilation photon upconversion (TTA-UC) is a process where two low-energy photons are converted into one higher-energy photon. A crucial component for an efficient upconversion process is the statistical probability factor (f), defined as the probability of the formation of a high-energy singlet state upon coupling of two low-energy triplet states. Theoretically, f depends on the energy level distribution, molecular orientation, inter-triplet exchange coupling of triplet dyads, and spin-mixing of resulting spin states (singlet, triplet, and quintet). However, experimental values of f for acene-based annihilators have been subject to large variations due to many factors that have resulted in the reporting of different f values for the same molecule. In this work, we discuss these factors by studying perylene as a case study annihilator, for which by far the largest variation in f = 16 to 100% has been reported. We systematically investigated the TTA-UC of PdTPBP:perylene, as a sensitizer-annihilator pair and obtained the experimental f = 17.9 ± 2.1% for perylene in THF solution. This limits the maximum TTA-UC quantum yield to 9.0% (out of 50%) for this annihilator. We found that such a low f value for perylene is largely governed by the energy-gap law where higher non-radiative losses due to the small energy gap between 2 × T1 and T2 affect the probability of singlet formation. Interestingly, we found this observation true for other acene-based annihilators whose emission ranges from the UV to the yellow region, thus providing a blueprint for future design of efficient TTA-UC systems

Author

Lukas Naimovičius

Institute of Material Science of Barcelona (ICMAB)

Vilnius University

Edvinas Radiunas

Vilnius University

Manvydas Dapkevičius

Vilnius University

Pankaj Bharmoria

Institute of Material Science of Barcelona (ICMAB)

Kasper Moth-Poulsen

Polytechnic University of Catalonia

Catalan Institution for Research and Advanced Studies

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Institute of Material Science of Barcelona (ICMAB)

Karolis Kazlauskas

Vilnius University

Journal of Materials Chemistry C

20507526 (ISSN) 20507534 (eISSN)

Vol. 11 42 14826-14832

Molecular Solar Thermal energy storage systems (MOST)

European Commission (EC) (EC/H2020/951801), 2020-09-01 -- 2024-02-29.

Swedish Energy Agency (2019-010724), 2019-05-07 -- 2019-09-03.

Photo Thermal Management Materials.Acronym: PHOTERM

European Commission (EC) (EC/H202/101002131), 2021-10-01 -- 2026-09-30.

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

DOI

10.1039/d3tc03158f

More information

Latest update

11/24/2023