Ultralow‐Transition‐Energy Organic Complex on Graphene for High‐Performance Shortwave Infrared Photodetection

Abstract

Room‐temperature, high‐sensitivity, and broadband photodetection up to the shortwave infrared (SWIR) region is extremely significant for a wide variety of optoelectronic applications, including contamination identification, thermal imaging, night vision, agricultural inspection, and atmospheric remote sensing. Small‐bandgap semiconductor‐based SWIR photodetectors generally require deep cooling to suppress thermally generated charge carriers to achieve increased sensitivity. Meanwhile, the photogating effect can provide an alternative way to achieve superior photosensitivity without the need for cooling. The optical photogating effect originates from charge trapping of photoinduced carriers at defects or interfaces, resulting in an extremely high photogain (106 or higher). Here, a highly sensitive SWIR hybrid photodetector, fabricated by integrating an organic charge transfer complex on a graphene transistor, is reported. The organic charge transfer complex (tetrathiafulvalene–chloranil) has an exceptional low‐energy intermolecular electronic transition down to 0.5 eV, with the aim of achieving efficient SWIR absorption for wavelengths greater than 2 µm. The photogating effect at the organic complex and graphene interface enables an extremely high photogain and a high detectivity of ≈1013 Jones, along with a response time of 8 ms, at room temperature for a wavelength of 2 µm.

2D van der Waals Heterojunction of Organic and Inorganic Monolayers for High Responsivity Phototransistors

“…Overall, hybrid organic-inorganic photodetectors based on a 1L-MoS 2 /BTBT-SAM heterojunction were successfully prepared, in which the efficient dissociation of photoinduced charge carrier and reduced recombination result in sensitive current multiplication as well as a remarkable high EQE in organic-inorganic photodetectors. [41,42] More than 20 1L-MoS 2 /BTBT-SAM heterojunction transistor devices were characterized and they show similar device performances. Besides, the electrical performances of 1L-MoS 2 contacting with both source and drain electrodes were investigated for comparison (Figure 4f).…”

High Performance Ternary Organic Phototransistors with Photoresponse up to 2600 nm at Room Temperature

“…Table S1, Supporting Information depicts the comparison in photoresponse performance of reported organic IR phototransistors and ours. [ 3,4,14,23,31,33,35–37 ]…”

Recent Progress of Methods to Enhance Photovoltaic Effect for Self‐Powered Heterojunction Photodetectors and Their Applications in Inorganic Low‐Dimensional Structures

“…Nanoscale materials that combine both inorganic and organic components can act as semiconductors. [ 160,161 ] Novel physical and chemical properties can be created from strong interactions between the organic and inorganic units. [ 145 ] The presence of aggregated nanostructures at the organic—inorganic interface can induce optical or electronic properties, which are distinct from their individual components, i.e., synergistic effects enhance the performance.…”

“…Furthermore, Si/metal oxide heterojunctions, such as Si/ZnO, Si/TiO 2 , and Si/CuO are emerging as promising candidates because metal oxide semiconductors have the benefits of facile fabrication as well as superior electronic and optical properties. [ 161 ] By introducing the pyro‐phototronic effect, which is derived from wurtzite structured CdS, the self‐powered p‐Si/n‐CdS PD shows a broadband response (325 to 1550 nm) under 0 bias voltage and a fast response speed. Upon 325 nm laser illumination, the rise‐ and decay‐time of the self‐powered PD are 245 and 277 µs, respectively.…”

“…The PD showed good photosensitivity for 920 nm light with an on–off ratio of 5.24 × 10 3 , a responsivity of 0.33 A W −1 , a specific detectivity of 1.6 × 10 13 Jones, and a photoresponse speed of 823/356 µs at 0 V bias voltage. [ 161 ] A highly sensitive and self‐powered NIR PD, based on PdSe 2 /pyramid Si heterojunction arrays, which was fabricated through simple selenization of predeposited Pd nanofilm on black Si, was reported. The as‐fabricated hybrid device showed an excellent photoresponse with a large on/off ratio of 1.6 × 10 5 , a responsivity of 456 mA W −1 , and a high specific detectivity of up to 9.97 × 10 13 Jones at 980 nm illumination at 0 bias voltage.…”