CHAW-KEONG YONGMusser, Andrew JAndrew JMusserBayliss, Sam LSam LBaylissLukman, StevenStevenLukmanTamura, HiroyukiHiroyukiTamuraBubnova, OlgaOlgaBubnovaHallani, Rawad KRawad KHallaniMeneau, AurélieAurélieMeneauResel, RolandRolandReselMaruyama, MunetakaMunetakaMaruyamaHotta, ShuShuHottaHerz, Laura MLaura MHerzBeljonne, DavidDavidBeljonneAnthony, John EJohn EAnthonyClark, JennyJennyClarkSirringhaus, HenningHenningSirringhaus2022-12-162022-12-162017-07-122041-1723https://scholars.lib.ntu.edu.tw/handle/123456789/626519Entanglement of states is one of the most surprising and counter-intuitive consequences of quantum mechanics, with potent applications in cryptography and computing. In organic materials, one particularly significant manifestation is the spin-entangled triplet-pair state, which mediates the spin-conserving fission of one spin-0 singlet exciton into two spin-1 triplet excitons. Despite long theoretical and experimental exploration, the nature of the triplet-pair state and inter-triplet interactions have proved elusive. Here we use a range of organic semiconductors that undergo singlet exciton fission to reveal the photophysical properties of entangled triplet-pair states. We find that the triplet pair is bound with respect to free triplets with an energy that is largely material independent (∼30 meV). During its lifetime, the component triplets behave cooperatively as a singlet and emit light through a Herzberg-Teller-type mechanism, resulting in vibronically structured photoluminescence. In photovoltaic blends, charge transfer can occur from the bound triplet pairs with >100% photon-to-charge conversion efficiency.enSINGLET-EXCITON-FISSION; ELECTRONIC-STRUCTURE; TETRACENE CRYSTALS; CHARGE-TRANSFER; QUANTUM EFFICIENCY; THIN-FILMS; PENTACENE; ANNIHILATION; FLUORESCENCE; DYNAMICS[SDGs]SDG7journal article10.1038/ncomms15953286996372-s2.0-85024132897WOS:000405270100001https://api.elsevier.com/content/abstract/scopus_id/85024132897