Shi, YupingYupingShiRoy, Partha P.Partha P.RoyHigashitarumizu, NaokiNaokiHigashitarumizuLee, Tsung -YenTsung -YenLeeLi, QuanweiQuanweiLiJavey, AliAliJaveyLandfester, KatharinaKatharinaLandfesterMcculloch, IainIainMccullochFleming, Graham R.Graham R.Fleming2025-08-282025-08-282025-04-290027-842410.1073/pnas.2413850122https://d8.irins.org/handle/IITG2025/1920840261928A combination of ultrafast, long-range, and low-loss excitation energy transfer from the photoreceptor location to a functionally active site is essential for cost-effective polymeric semiconductors. Delocalized electronic wavefunctions along pi-conjugated polymer (CP) backbone can enable efficient intrachain transport, while interchain transport is gen erally thought slow and lossy due to weak chain-chain interactions. In contrast to the conventional strategy of mitigating structural disorder, amorphous layers of rigid CPs, exemplified by highly planar poly(indacenodithiophene-co-benzothiadiazole) (IDT-BT) donor-accepter copolymer, exhibit trap-free transistor performance and charge-carrier mobilities similar to amorphous silicon. Here, we report long-range exciton transport in HJ-aggregated IDTBT thin-film, in which the competing exciton transport and exciton-exciton annihilation (EEA) dynamics are spectroscopically separated using a phase-cycling-based scheme and shown to depart from the classical diffusion-limited and strong-coupling regime. In the thin film, we find an annihilation-limited mec hanism with << 100% per-encounter annihilation probability, facilitating the mini mization of EEA-induced excitation losses. In contrast, excitons on isolated IDTBT chains diffuse over 350 nm with 0.56 cm2 s-1 diffusivity, before eventually annihilating with unit probability on first contact. We complement the pump-probe studies with temperature-dependent photocurrent and EEA measurements from 295 K to 77 K and find a remarkable correspondence of annihilation rate and photocurrent activation energies in the 140 K to 295 K temperature range.en-USScience & Technology - Other TopicsArticlehttps://escholarship.org/uc/item/3fh51400https://v2.sherpa.ac.uk/id/publication/103381091-649029-04-20252410000000Article0WOS:001484238200001