Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited ...Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited SF materials as a result of stringent requirements for atypical energetic arrangement and high ambient stability.Here we show that excited-state antiaromaticity(ESAA)relief can be used to simultaneously regulate the energy separation between T_(1) and S_(0) and design SF-capable materials with favorable energetic conditions and excellent stability.We achieve this by facilitatingπ-electron migration between the seven-and fivemembered rings in acepleiadylene(APD),which alleviates Baird’s antiaromaticity in the T_(1) state while maintaining Hückel’s aromaticity in S_(0).This leads to a lowered T_(1)’s energy relative to S_(0).Aromaticity index calculations reveal the aromaticity reversal and electron density redistribution between S_(0) and T_(1) to mitigate ESAA.This results in an energetic relationship suitable for SF,enabling a rapid fission process with an impressive yield of 165%.Moreover,ESAA relief endows APD with superior stability under ambient conditions.Our work not only introduces a new SF scaffold based on nonbenzenoid hydrocarbons,but it also provides valuable insights for the design of stable SF-active materials.展开更多
基金supported by the National Natural Science Foundation of China(grant nos.22173062,21833005,22090022,and 22275125)the Beijing Natural Science Foundation of China(grant nos.Z230019 and 2212005)the Youth Innovative Research Team of Capital Normal University.
文摘Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited SF materials as a result of stringent requirements for atypical energetic arrangement and high ambient stability.Here we show that excited-state antiaromaticity(ESAA)relief can be used to simultaneously regulate the energy separation between T_(1) and S_(0) and design SF-capable materials with favorable energetic conditions and excellent stability.We achieve this by facilitatingπ-electron migration between the seven-and fivemembered rings in acepleiadylene(APD),which alleviates Baird’s antiaromaticity in the T_(1) state while maintaining Hückel’s aromaticity in S_(0).This leads to a lowered T_(1)’s energy relative to S_(0).Aromaticity index calculations reveal the aromaticity reversal and electron density redistribution between S_(0) and T_(1) to mitigate ESAA.This results in an energetic relationship suitable for SF,enabling a rapid fission process with an impressive yield of 165%.Moreover,ESAA relief endows APD with superior stability under ambient conditions.Our work not only introduces a new SF scaffold based on nonbenzenoid hydrocarbons,but it also provides valuable insights for the design of stable SF-active materials.
