Photomultiplication-type Organic Photodetectors Based on Non-fullerene Acceptor IEICO-4F

With the solution-processing method, photomultiplication (PM)-type organic photodetectors (OPDs) were fabricated with the structures of ITO/PEDOT: PSS/P3HT: IEICO-4F/Al and ITO/PEDOT: PSS/P3HT: O-IDTBR/Al, in which non-fullerene acceptor materials IEICO-4F and O-IDTBR were used as electron acceptors. The highest external quantum efficiency (EQE) of the device based on IEICO-4F-can reach 7 220% and 1 610% at 400 nm and 790 nm, respectively. Under -15 V bias, the EQE of IEICO-4F-based device exceeds 100% in the range of 300 to 840 nm, which is about 120 nm broader than O-IDTBR-based-devices (320 to 740 nm). Compared with the O-IDTBR-based device under -15 V bias, the EQEs (2 630%, 1 220%, 1 900%, 409%) of the IEICO-4F-based device at the wavelength of 400, 510, 600 and 790 nm are 1.7, 1.2, 0.5 and 24.5 times larger, respectively. In addition, the detectivity of IEICO-4F-based device at 400, 510, 600 and 790 nm (4.8×10¹², 2.8×10¹², 5.2×10¹² and 1.5×10¹² cm·Hz^1/2·W^-1) are 3.2, 2.5, 1.8 and 30.6 times as large as those of the O-IDTBR-based device, respectively. These results show that the use of non-fullerene materials IEICO-4F (narrower band gap) with absorption more complementary to P3HT as electron acceptors is beneficial for improving the performance of PM-type OPDs, especially the responsivity and detectivity in near-infrared region, with broadened spectral response range.