Molecular‐Switch‐Embedded Solution‐Processed Semiconductors

Abstract

oxides, [44][45][46][47][48] inorganic nanocrystals, [49][50][51][52][53] and quantum dots. [54][55][56][57] The cornerstones in the history of these solution-processed semiconductors are as follows: 1) understanding of the fundamental physics of processes such as charge generation and transport; 2) optimization of their electronic/optoelectronic performances based on the development of new materials and/ or device architectures; 3) development of further functionalities of these materials typically by embedding other functional materials. The most frequently utilized material family in the third stage was the photochromic molecular switch, which showed binary isomerization between two distinct isomers in terms of the conjugation length (diarylethene (DAE)), trans/cis configuration (azobenzene), and ionic nature and dipole moment (spiropyran (SP) and spirooxazine (SPOx)). [58][59][60][61][62] These molecular switches are typically responsive to a light stimulus; therefore, molecular-switch-embedded solution-processed semiconductors possess possibility of realizing multifunctionality with nondestructive and effective optical control. Organic chemists have been developing sophisticated synthetic processes for delicate control of the physical properties of molecular switches, enabling broad and excellent responsivities to various external stimuli. [63][64][65][66][67][68][69][70][71] While previous reviews had analyzed the performances of molecular-switch-embedded semiconductors based on the type of molecular switch, semiconductor, or device, this review conducts an analysis purely based on the optoelectronic transition mechanism for a more comprehensive and integrated perspective. This approach may allow researchers to discover relevant molecular-switch-related operating mechanisms for their own studies. For this reason, the review is structured as follows: 1) semiconductor trap-level control, 2) semiconductor bulk-resistance control, 3) semiconductor doping control, 4) semiconductor junction control, and 5) other interesting mechanisms. Although described separately, all these mechanisms have in common the utilization of apparently different electron accepting/donating properties of two isomers of each molecular switch. In other words, researchers are tailoring expressions to fit the different environments and materials in which molecular switches are being applied. At the beginning of each subchapter, the mechanism of the corresponding method is explained along with a schematic diagram (Figure 1).Recent improvements in the performance of solution-processed semiconductor materials and optoelectronic devices have shifted research interest to the diversification/advancement of their functionality. Embedding a molecular switch capable of transition between two or more metastable isomers by light stimuli is one of the most straightforward and widely accepted methods to potentially realize the multifunctionality of optoelectronic devices. A molecular switch embedded in a semiconductor can effectively control various pa...

A photo-responsive organic electrochemical transistor

“…37 The process of blending is aimed at avoiding phase segregation while favoring intermixing towards a maximal degree of intercomponent interfacing, as inspired by van der Waals heterostructures. 43 In our photoswitchable blend, the pgBTTT polymer imparts mixed ionicelectronic conductivity whereas the OEG-SP additive confers a photoresponsive nature to the hybrid material. These two components have been mixed in a 20% m/m proportion of OEG-SP in pgBTTT and deposited as drop-cast thin films from CHCl 3 solutions at various concentrations.…”

MOF-enabled high-density 2D molecular crystal optoelectronic memory transistor with floating gate architecture

“…[3][4][5] Benefiting from the designability and flexibility of organic semiconductor materials, organic memory devices have garnered widespread attention and development to meet the ever-growing demand for high storage density. [6][7][8][9] Among various types of devices, field-effect floating gate transistor memories are promising due to their ability to preserve charge-trapping centers within the device, preventing slow release of charges and thus achieving robust storage capabilities. [10][11][12][13] Moreover, unlike traditional electrically programmable memory devices that read information, fieldeffect floating gate transistors involve a charge-trapping layer that can form an additional control electric field by capturing photogenerated carriers, providing a degree of freedom in the optical control of storage capabilities.…”

Photophore‐Anchored Molecular Switch for High‐Performance Nonvolatile Organic Memory Transistor

“…[ 20 , 21 , 22 ] One widely accepted approach for achieving multifunctionality in OFETs involves incorporating molecular switches capable of inducing transitions between two or more metastable isomers through light stimuli. [ 23 , 24 ] Previous studies have shown that integrating a molecular switch within an OSC facilitates effective control of trap levels, thereby resulting in photoprogrammable OFETs. [ 25 , 26 , 27 , 28 , 29 ] Among the photochromic molecular switches commonly used in combination with OSCs, diarylethenes (DAEs) have emerged as a prominent choice.…”