Enhancing the Performance of Non-Fullerene Organic Solar Cells Using Regioregular Wide-Bandgap Polymers

To better utilize sunlight, organic solar cells (OSCs) should contain a narrow-bandgap non-fullerene acceptor blended with a wide-bandgap polymer donor as the active layer. Here we developed a regioregular wide-bandgap polymer (denoted as reg-PThE) as a donor material to enhance the performance of non-fullerene OSCs. Compared with the corresponding random polymer (ran-PThE), reg-PThE in films showed closer packing of the polymer backbone and a larger absorption coefficient. Devices based on reg-PThE:FTIC achieved a high power conversion efficiency (PCE) of 12.07%. Conversely, devices based on ran-PThE:FTIC only realized a PCE of 9.89%. When ITTC was used as the acceptor, PCEs of 11.21% and 8.38% were obtained for reg-PThE- and ran-PThE-based devices, respectively. Semitransparent OSCs with reg-PThE:ITTC as the active layer demonstrated a PCE of 8.69% and an average visible transmittance of ∼25%. Our results revealed that a regioregular polymer is better than the corresponding random polymer to maximize the PCE of non-fullerene OSCs