Thermally Stable Organic Field‐Effect Transistors Based on Asymmetric BTBT Derivatives for High Performance Solar‐Blind Photodetectors

Abstract

High‐performance solar‐blind photodetectors are widely studied due to their unique significance in military and industrial applications. Yet the rational molecular design for materials to possess strong absorption in solar‐blind region is rarely addressed. Here, an organic solar‐blind photodetector is reported by designing a novel asymmetric molecule integrated strong solar‐blind absorption with high charge transport property. Such alkyl substituted [1]benzothieno[3,2‐b][1]‐benzothiophene (BTBT) derivatives C n ‐BTBTN ( n = 6, 8, and 10) can be easily assembled into 2D molecular crystals and perform high mobility up to 3.28 cm 2 V −1 s −1 , which is two orders of magnitude higher than the non‐substituted core BTBTN. C n ‐BTBTNs also exhibit dramatically higher thermal stability than the symmetric alkyl substituted C8‐BTBT. Moreover, C10‐BTBTN films with the highest mobility and strongest solar‐blind absorption among the C n ‐BTBTNs are applied for solar‐blind photodetectors, which reveal record‐high photosensitivity and detectivity up to 1.60 × 10 7 and 7.70 × 10 14 Jones. Photodetector arrays and flexible devices are also successfully fabricated. The design strategy can provide guidelines for developing materials featuring high thermal stability and stimulating such materials in solar‐blind photodetector application.

Reducing Contact Resistance in Organic Field-Effect Transistors: A Comprehensive Comparison between 2D and Microrod Single Crystals

“…The nonlinear I D profile of the microrod OFET implies the necessity of a high V D to induce a sufficient electric field in the contact region to enable effective carrier injection. 34 To verify the reliability of the device behavior in Figure 4, 30 microrod and 2D OFETs were tested, and similar results were observed. It is thus concluded that R C in the 2D OFET is much smaller than that in the microrod OFET, which may have a great influence on their device parameter evaluation.…”

“…The 2D device shows good linearity in the linear regime (Figure b), which is completely different from the superlinear I D increase at low V D for the microrod device (Figure d). The nonlinear I D profile of the microrod OFET implies the necessity of a high V D to induce a sufficient electric field in the contact region to enable effective carrier injection . To verify the reliability of the device behavior in Figure , 30 microrod and 2D OFETs were tested, and similar results were observed.…”

Comprehensive Study on the Mobility Anisotropy of Benzothieno[3,2-b][1]benzothiophenes: Toward Isotropic Charge-Transport Properties

“…To prove this hypothesis, we successfully synthesized 2,7-bis­(4-ethylphenyl) benzothieno­[3,2- b ]­[1] benzothiophene (DBEP-BTBT), in which ethylbenzene groups are introduced at 2,7-positions of the BTBT core. It is worth mentioning that BTBT has been extensively applied as a platform for constructing the best-performing small-molecule semiconductors, − but its effect on mobility isotropy has not been fully understood. Herein, we first aim to systematically study the mobility anisotropy of three types of BTBT derivatives, including mono-, asymmetrically, and symmetrically substituted BTBTs, and study their potential to achieve low anisotropy in mobility.…”

Room-temperature smectic liquid crystal monolayers for field-effect transistors

“…Organic field-effect transistors (OFETs) have attracted widespread attention due to their potential applications in flexible electronic devices and circuits. [1][2][3][4][5][6][7] Exploring new materials that are compatible with low-cost solution-processing techniques has been one of the hot topics in organic semiconductors. Among them, organic liquid crystals, an archetypal soft matter material with an intrinsic ability to self-organize into ordered mesophases between the crystal and liquid phases, have superior solubility in common organic solvents.…”