Light-responsive spiropyran based polymer thin films for use in organic field-effect transistor memories

Abstract

Light-responsive spirotype compounds have been receiving attention as attractive smart materials because of their various potential applications in organic optoelectronic devices, based on organic field-effect transistors (OFETs). However, it still remains a challenge to apply the organic flash memory devices using spirotype compounds due to the relatively poor development of new photosensitive electret materials.Here, we report the synthesis of a novel photosensitive polymer electret material, spiropyran, containing poly(3,5-benzoic acid hexafluoroisopropylidene diphthalimide) (6FDA-DBA-SP), and the development of light-responsive flexible memory devices using the 6FDA-DBA-SP electret layer. The charge trapping properties of 6FDA-DBA-SP under light illumination were enhanced by the electron withdrawing properties and lowering energetic barrier of charge trapping between 6FDA-DBA-SP and pentacene analysed by measuring the electronic structures at the pentacene/6FDA-DBA-SP interfaces. The resulting OFETs showed enlarged hysteresis under white-light illumination and exhibited bi-stable current states after the light-assisted programing and erasing processes, and they were utilized in non-volatile flexible memory device applications. † Electronic supplementary information (ESI) available: Synthetic methods and analysis of 6FDA-DBA-SP; the 1 H-NMR spectrum, DSC curves, and TGA curves of 6FDA-DBA and 6FDA-DBA-SP; UV-Vis absorption spectra of SP-OH, 6FDA-DBA, and 6FDA-DBA-SP; electrical characteristics table of the SP-OFETs; transfer characteristics in the saturation regime of the SP-OFETs; transfer characteristics of the SP-OFETs during successive sweeps under different conditions (10 sweeps under dark conditions and 1 sweep under white-light); transfer characteristics of SP-OFETs as a function of applied bias time or voltage under dark conditions; transfer characteristics of SP-OFETs as a function of applied bias time under white-light illumination (sweeping from À40 V to 40 V); transfer characteristics of pentacene OFETs based on a polystyrene layer; comparative UPS spectra of pentacene and 6FDA-DBA-SP films in the dark or under white-light; (ahn) 2 versus hn plot of 6FDA-DBA-SP and pentacene films; current response to one-cycle switching behavior of SP-OFET memory devices; and transfer characteristics of the flexible SP-OFETs before and after bending in the dark. See

Poly(azomethine‐imide)s containing siloxane moities: Optical, thermal, mechanical, and morphological properties

“…Bulky CF 3 groups in HFIPA are a strongly electron with‐drawing group. As known, these groups decrease the conjugated structure and electron density of 132F and 134F …”

Recent Advances of Flexible Data Storage Devices Based on Organic Nanoscaled Materials

“…Jeong et al synthesized a novel photosensitive polymer and employed it as polymer electrets in a light‐responsive flexible memory. The photosensitive electret is a kind of spiropyran based polymer which is containing a polyimide components with a donor–acceptor system and named as 6FDA‐DBA‐SP.…”

Multi-Stimuli-Responsive Field-Effect Transistor with Conjugated Polymer Entailing Spiropyran in the Side Chains

“…[21][22][23][24] In recent years, FETs with external-field tunable electrical properties other than electrical voltage have been of considerable interest. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Since the output current could be controlled simultaneously and independently by voltage, as well as other external fields, it is possible to integrate complex functionalities, such as memory devices, switches, and complex logic operations, in a single FET device. [41][42][43] Often, light is used as the external stimuli for optically tunable FETs.…”

“…[41][42][43] Often, light is used as the external stimuli for optically tunable FETs. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] In fact, their fabrications have been achieved by utilizing photochromic molecules, able to undergo reversible light-induced interconversions between two isomers. 41 For instance, Samorì and coworkers 25 blended diarylethene derivative with P3HT [poly(3-hexylthiophene)] to generate a semiconducting film, which showed optically reversible FET with characteristic bi-stable states upon alternating UV and visible light irradiations.…”