Low roll off radiation efficiency of charge transfer state excitons based on organic photovoltaic and electroluminescent integrated device

Organic photovoltaic and electroluminescent (EL) integrated devices were fabricated with a heterojunction structure consisting of Rubrene electron donor and fullerene electron acceptor. By using infrared transmission filter and near infrared detector, the ELCT signals of charge transfer state (CTS) excitons were separated from the light emission of singlet (ELSE) or triplet exciton. The EL external quantum efficiencies from pure CTS excitons exhibited ultra-low roll off characteristics. Meanwhile, an improved exponential model was proposed to accurately simulate the relationship between the light emission photons of CTS and singlet excitons versus applied bias, which illuminated the roll off of ELCT and ELSE.