Paper Title
Long Lived-Charge Separation of Ultrafast Bimolecular Electron Transfer At Pce10 and C60 Interfaces (Donor/Acceptor System)

In the organic photovoltaic (OPV) devices, the photoconversion efficiency (PCE) is governed by the fundamental photophysics processes taking place at the Donor/Acceptor (D/A) interface which account for the overall charge carrier collection at the respective electrodes. A profound understanding of the ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) are paramount in enhancing the PCEs of the solar cell devices. In this study, a combination of steady-state and femtosecond transient absorption spectroscopies with broadband capabilities are used to explore and decipher the photoinduced charge carrier dynamics at the D/A interfaces between π-conjugated polymer PCE10 and fullerene acceptor. Our experimental results verified the efficient and ultrafast (sub-picosecond) photoinduced electron transfer (ET) from the PCE10 polymer to fullerene acceptor C60, leading to a long-lived PCE10⁺• radical cation and a C60 fullerene radical anion. Notably, the slow charge recombination (CR) and fast electron transfer (ET) makes the current PCE10/C60 system ideal for its potential use in the bulk heterojunction (BHJ) solar cells. Keywords- Ultrafast laser spectroscopy, Interfacial charge transfer, Charge separation, bimolecular system (OPV).