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The prevalence of background hole doping in tin halide perovskites usually dominates their recombination dynamics. The addition of excess Sn halide source to the precursor solution is the most frequently used approach to reduce the hole doping and reveals photo-carrier dynamics related to defects activity. This study presents an experimental and theoretical investigation on defects under light irradiation in tin halide perovskites by combining measurements of photoluminescence with first principles computational modeling. It finds that tin perovskite thin films prepared with an excess of Sn halide sources exhibit an enhancement of the photoluminescence intensity over time under continuous excitation in inert atmosphere. The authors propose a model in which light irradiation promotes the annihilation of V Sn 2- /Sn i 2+ Frenkel pairs, reducing the deep carrier trapping centers associated with such defect and increasing the radiative recombination. Importantly, these observations can be traced in the open-circuit voltage dynamics of tin-based halide perovskite solar cells, implying the relevance of controlling the Sn photochemistry to stabilize tin perovskite devices., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

The syntheses of four triptycene-bis(aroyleneimidazole)s-the missing links with respect to the previously reported triptycene-mono(aroyleneimidazole)s and triptycene-tris(aroyleneimidazole)s-are presented. Their optoelectronic properties and use as non-fullerene acceptors in organic photovoltaics with poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}[3-fluoro-2-(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl) (PTB7) as a donor are described; these systems reach a maximum power conversion efficiency of 2 %. Furthermore, the effect of molecular symmetry on the photovoltaic device performance is discussed., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)