Molecular packing determines singlet exciton fission in organic semiconductors

K Kolata, T Breuer, G Witte, S Chatterjee - ACS nano, 2014 - ACS Publications
K Kolata, T Breuer, G Witte, S Chatterjee
ACS nano, 2014ACS Publications
Carrier multiplication by singlet exciton fission enhances photovoltaic conversion
efficiencies in organic solids. This decay of one singlet exciton into two triplet states allows
the extraction of up to two electrons per harvested photon and, hence, promises to overcome
the Shockley–Queisser limit. However, the microscopic mechanism of singlet exciton fission,
especially the relation between molecular packing and electronic response, remains
unclear, which therefore hampers the systematic improvement of organic photovoltaic …
Carrier multiplication by singlet exciton fission enhances photovoltaic conversion efficiencies in organic solids. This decay of one singlet exciton into two triplet states allows the extraction of up to two electrons per harvested photon and, hence, promises to overcome the Shockley–Queisser limit. However, the microscopic mechanism of singlet exciton fission, especially the relation between molecular packing and electronic response, remains unclear, which therefore hampers the systematic improvement of organic photovoltaic devices. For the model system perfluoropentacene, we experimentally show that singlet exciton fission is greatly enhanced for a slip-stacked molecular arrangement by addressing different crystal axes featuring different packing schemes. This reveals that the fission process strongly depends on the intermolecular coupling: slip-stacking favors delocalization of excitations and allows for efficient exciton fission, while face-to-edge molecular orientations commonly found in the prevailing herringbone molecular stacking patterns even suppress it. Furthermore, we clarify the controversially debated role of excimer states as intermediary rather than competitive or precursory. Our detailed findings serve as a guideline for the design of next-generation molecular materials for application in future organic light-harvesting devices exploiting singlet exciton fission.
ACS Publications
以上显示的是最相近的搜索结果。 查看全部搜索结果