Spin-statistical factor in the triplet-triplet annihilation of anthracene triplets

Plasmon-enhanced homogeneous and heterogeneous triplet–triplet annihilation by gold nanoparticles

“…[7] 50 Thus sensitized singlet oxygen generation is in essence a heterogeneous TTA process. [19] Singlet oxygen plays a critical role in photodynamic therapy against both cancers and bacteria. [20] There have been a lot of efforts in identifying, designing and synthesizing molecules as efficient sensitizers.…”

Transition-Metal Complexes for Triplet–Triplet Annihilation-Based Energy Upconversion

“…The spin manifold of the triplet encounters of the acceptors is governed by the spinstatistics, which has been reviewed by Saltiel et al [16,17]. When two excited triplets interact, the spin multiplicities in a diffusion-controlled environment result in nine encounter-pair spin states which are composed of three distinct sublevels, namely, five quintet, three triplet, and one singlet, and are produced with the equal probability.…”

“…Then the upper limit, based on the spin-statistics probability of forming the singlet excited annihilator (1/9), would be just 5.55 %, given that both the quantum yield of fluorescence and the efficiency of TTET from the sensitizer to the emitter are unity. However, the triplets (and likely also the quintets) formed upon annihilation can be recycled, which are involved in the TTA again until they decay via the singlet pathway [17,18]. Furthermore, the quintet state of polyaromatic organic compounds is often inaccessible [19].…”

Room temperature long-lived triplet excited state of fluorescein in N^N Pt(II) bisacetylide complex and its applications for triplet–triplet annihilation based upconversions

“…With selective excitation of the triplet sensitizer, the energy is transferred to the triplet acceptor via tripletetriplet-energytransfer (TTET), then two acceptor molecules at the triplet state will annihilate to produce an acceptor molecule at the singlet excited state. According to the spin statistical rule, the probability of producing of the singlet excited states in the annihilation product is 11.1% [7,8,49].…”