No abstract

The incapability of modulating the photoresponse of assembled heterostructure devices has remained a challenge for the development of optoelectronics with multifunctionality. Here, a gatetunable and anti-ambipolar phototransistor is reported based on 1D GaAsSb nanowire/2D MoS 2 nanoflake mixed-dimensional van der Waals heterojunctions. The resulting heterojunction shows apparently asymmetric control over the anti-ambipolar transfer characteristics, possessing potential to implement electronic functions in logic circuits. Meanwhile, such an anti-ambipolar device allows the synchronous adjustment of band slope and depletion regions by gating in both components, thereby giving rise to the gate-tunability of the photoresponse. Coupled with the synergistic effect of the materials in different dimensionality, the hybrid heterojunction can be readily modulated by the external gate to achieve a highperformance photodetector exhibiting a large on/off current ratio of 4 × 10 4 , fast response of 50 μs, and high detectivity of 1.64 × 10 11 Jones. Due to the formation of type-II band alignment and strong interfacial coupling, a prominent photovoltaic response is explored in the heterojunction as well. Finally, a visible image sensor based on this hybrid device is demonstrated with good imaging capability, suggesting the promising application prospect in future optoelectronic systems.

1]benzothieno[3,2-b]benzothiophene (BTBT), with two benzene rings as the outermost rings, is referred to as diacene-fused ladder-type π-conjugated thienothiophenes. During the last three decades, derivatives based on BTBT core have been extensively studied due to their tremendous application prospects in organic field-effect transistors (OFETs) and organic optoelectronic devices. In order to further advance the development of organic electronics, new materials are constantly being synthesized and new methods are constantly evolving. This review mainly focuses on the crystal and electronic structures of BTBT derivatives, the soluble and thermal properties, the fabrication methods, as well as the strategies for performance improvement and optoelectronic applications including OFETs, photodetectors, synaptic devices, and organic light-emitting transistors. As one of the most promising organic materials, the insight into BTBT-based molecules will accelerate their potential application and provide important reference value for the development toward commercialized and industrialized organic semiconducting products.

Continuous miniaturization of semiconductor devices is the key to boosting modern electronics development. However, this downscaling strategy has been rarely utilized in photoelectronics and photovoltaics. Here, in this work, a full-van der Waals (vdWs) 1D p-Te/2D n-Bi 2 O 2 Se heterodiode with a rationally designed nanoscale ultra-photosensitive channel is reported. Enabled by the dangling bond-free mixed-dimensional vdWs integration, the Te/Bi 2 O 2 Se type-II diodes show a high rectification ratio of 3.6 × 10 4 . Operating with 100 mV reverse bias or in a self-power mode, the photodiodes demonstrate excellent photodetection performances, including high responsivities of 130 A W −1 (100 mV bias) and 768.8 mA W −1 (self-power mode), surpassing most of the reports of other heterostructures. More importantly, a superlinear photoelectric conversion phenomenon is uncovered in these nanoscale full-vdWs photodiodes, in which a model based on the in-gap trap-assisted recombination is proposed for this superlinearity. All these results provide valuable insights in light-matter interactions for further performance enhancement of photoelectronic devices.