In phototransistors, the photovoltaic‐induced current is proportional to the turn‐on voltage shift and the total number of trapped charges. However, it is challenging to obtain a high turn‐on voltage shift simply by using minority carrier trap sites because high‐concentration carrier trap sites introduce strong current traps and carrier recombination. In this study, spatially separated, hole/electron, dual traps are introduced into a phototransistor, demonstrating the possibility of combining hole and electron traps without and with illumination, respectively, to obtain a large turn‐on voltage shift. The near‐infrared phototransistor demonstrates a high light‐to‐dark current ratio (1 × 106) alongside a turn‐on voltage shift of 28 V. The current quenching of the charge trap is effectively compensated by the threshold voltage shift, resulting in an increase of the drain–source current. The dual traps induce a low‐noise current and a high photoresponsivity (5.26 × 103 A W–1) under the same gate voltage (Vg = 0 V), exhibiting an ultrahigh detectivity (D1/f∗ = 1.88 × 1015 Jones; Dshot∗= 8.21 × 1016 Jones).

We report a novel OPT working mode by photoelectric dual control. After each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by the device converting to accumulation mode when the light is on.

The fabrication of lateral polymer photodetectors (L-PPDs) is rarely reported in literature. Unlike vertical photodiode or phototransistor, it would be much more difficult to experimentally improve all of the performance metrics in lateral structure under long channel without compromising any of them. The performance metrics include charge separation, photomultiplication, trapped-charge relaxation, dark current, fast response and so on. In this research, L-PPDs with comparable performance to photodiodes were developed, and the photodetectors have the structure of quartz/Ag-NPs (1 nm)/ PMMA (30 nm)/PffBT4T-2OD:PC61BM (D/A ratio = 1:1.2; 140 nm)/Ag–Ag electrodes. A phase control of BHJ allows effective electrons to be trapped under high PCBM ratio, which simultaneously gives high charge separation and photomultiplication (gain = 161.5 at a current density of 73 mA/cm2). Moreover, photogenerated electrons trapped in active layer can be neutralized by photoinduced holes stored in Ag-NPs, resulting in an obvious decrease of dark current (specific detectivity, 5.26 × 1014 Jones; response time of rise and decay, 10–20 ms). The novel lateral topology of PPDs, which is similar to the architecture of inorganic photodetectors, has promising application potential.

In organic photodetectors, photomultiplication is mainly originated from interfacial and/or bulk charge traps, which induces slow response due to the slow release of trapped charges and strongly limits the optimization of the overall performance. This study has exhibited a remarkable case that the gain (>1) and response speed of the lateral photodetectors are promoted simultaneously and effectively by increasing the trap ratio. For lateral photodetectors with silver nanoparticles and PDPPBTT:PC 61 BM bulk heterojunction, the gain increases from 12.7 to 19.8 and the fall time decreases from 313.4 to 172.9 ms as the PC 61 BM ratio increases from 5:1 to 1:1. The lateral photodetector structure with a long electrode distance has been testified to play the key role for simultaneous promotion compared with vertical photodiodes, allowing the charges to trap well in the PC 61 BM-rich phase at a high PC 61 BM ratio and accumulation of multiple built-in electric fields. The long channel distance and silver nanoparticles also effectively restrain the increment of dark current with PC 61 BM loading, resulting in a high detectivity of 1.7 × 10 12 Jones under 0.031 mW cm −2 @ 820 nm. It is of great theoretical and practical value for the high-performance photodetectors with simultaneous high photomultiplication and quick response.