Delayed Luminescence Spectroscopy of Organic Photovoltaic Binary Blend Films: Probing the Emissive Non-geminate Charge Recombination

Organic photovoltaics: Following the direct photoexcitation of the low-energy optical gap PDI component in the F8BT:PDI photovoltaic blend film (step 1), charge generation takes place (steps 2, 3). Non-geminate charge recombination (step 4) results in the generation of delayed luminescence (DL) in the mu s time scale (step 5). The DL spectrum originates from an equilibrated charge-transfer (CT) state formed between the components of the composite. The F8BT-PDI CT complex has a ground state character (step 6).