Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octylox...Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octyloxythiophene bridges.BTP-out-4F with octyloxy side chains away from the central core exhibited large steric hindrance that restrained the rotational freedom between the thiophene bridge and end group but maintained free rotation between the central core and the thiophene bridge.In contrast,BTP-in-4F with octyloxy side chains close to the central core had much lower rotation freedom due to the non-covalent S⋯O interactions locked the central core,thiophene bridge and end group simultaneously,making BTP-in-4F have higher molecular crystallinity.On the other hand,the optical properties,energy levels and the blend morphology properties were significantly influenced,leading to distinctive photovoltaic performances.BTP-out-4F formed favorable energy level alignment and morphology when matching with PBDB-T donor,thus its device realized a much higher PCE of 13.32%,which was over 13 times than that of BTP-in-4F based device(PCE=0.97%).展开更多
Azaacene diimides are expected to possess deeplowest unoccupied molecular orbital (LUMO) levelsand narrower bandgaps while maintaining excellentsolubility and enhanced stability compared to theirparent acenes. However...Azaacene diimides are expected to possess deeplowest unoccupied molecular orbital (LUMO) levelsand narrower bandgaps while maintaining excellentsolubility and enhanced stability compared to theirparent acenes. However, the synthesis of fully conjugatedazaacenes has posed a long-term challenge. Inthis study, we report a stepwise oxidation approachto successfully synthesize a series of fully conjugatedtetraazahexacene diimides (TAHDIs). Through peripheryengineering, the targeted TAHDIs, featuringelectron-donating ethylenedioxy rings, exhibitedsignificantly enhanced stability, with a half-life time(τ1/2) of up to 65 h under ambient conditions.Furthermore, single-crystal structural elucidationrevealed a nearly planar geometry, with the imiderings slightly deviating from the skeleton plane. Notably,the LUMO levels were determined to be as lowas −4.68 eV for TAHDI-ad and could be noticeablyelevated to −4.53 eV through the attachment ofelectron-donating groups (TAHDI-ce). This workrepresents a rare example of an experimetally evidencedlow-lying LUMO level, providing an alternativestrategy for developing higher fully conjugatedazacene diimides, which have great promise in electronicsand molecular electronics.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21825502,22075190,21905185 and 22105135)Special funds for local science and technology development guided by the central government(No.2020ZYD004)+1 种基金the Foundation of State Key Laboratory of Polymer Materials Engineering(No.SKLPME 2017-2-04)the Fundamental Research Funds for the Central Universities.
文摘Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octyloxythiophene bridges.BTP-out-4F with octyloxy side chains away from the central core exhibited large steric hindrance that restrained the rotational freedom between the thiophene bridge and end group but maintained free rotation between the central core and the thiophene bridge.In contrast,BTP-in-4F with octyloxy side chains close to the central core had much lower rotation freedom due to the non-covalent S⋯O interactions locked the central core,thiophene bridge and end group simultaneously,making BTP-in-4F have higher molecular crystallinity.On the other hand,the optical properties,energy levels and the blend morphology properties were significantly influenced,leading to distinctive photovoltaic performances.BTP-out-4F formed favorable energy level alignment and morphology when matching with PBDB-T donor,thus its device realized a much higher PCE of 13.32%,which was over 13 times than that of BTP-in-4F based device(PCE=0.97%).
基金supported financially by the National Natural Science Foundation of China(NSFC,grant nos.22235005 and 22122503).
文摘Azaacene diimides are expected to possess deeplowest unoccupied molecular orbital (LUMO) levelsand narrower bandgaps while maintaining excellentsolubility and enhanced stability compared to theirparent acenes. However, the synthesis of fully conjugatedazaacenes has posed a long-term challenge. Inthis study, we report a stepwise oxidation approachto successfully synthesize a series of fully conjugatedtetraazahexacene diimides (TAHDIs). Through peripheryengineering, the targeted TAHDIs, featuringelectron-donating ethylenedioxy rings, exhibitedsignificantly enhanced stability, with a half-life time(τ1/2) of up to 65 h under ambient conditions.Furthermore, single-crystal structural elucidationrevealed a nearly planar geometry, with the imiderings slightly deviating from the skeleton plane. Notably,the LUMO levels were determined to be as lowas −4.68 eV for TAHDI-ad and could be noticeablyelevated to −4.53 eV through the attachment ofelectron-donating groups (TAHDI-ce). This workrepresents a rare example of an experimetally evidencedlow-lying LUMO level, providing an alternativestrategy for developing higher fully conjugatedazacene diimides, which have great promise in electronicsand molecular electronics.
