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Red-Selective Polymer Designed by Time-Dependent Density Functional Theory Calculation for Full-Color Image Sensing

2023-10-11T15:00:00Z

Title: Red-Selective Polymer Designed by Time-Dependent Density Functional Theory Calculation for Full-Color Image Sensing Author(s): Jeon, Woojin; Choi, Changwon; Jang, Yun Hee; Lansac, Yves Abstract: Strong color selective narrowband absorption is a major requirement for RGB-color- sensing photodiode components. The bioelectronic applications such as retina- prosthetic artificial vision would require flexible, biocompatible, and solution-treated polymer thin film for the strong color selective absorption. However, tuning a polymer for red color selective absorption is challenging, because the red color absorption in the region of 625-800 nm is often accompanied by green/blue color absorption in the region of 400-625 nm or by near-IR absorption in the region over 800 nm. In our study, for the strong red-selective absorption, we propose a narrow-wide-copolymer design rule which includes the following requirements: (1) HOMO and LUMO bands are localized in the narrow units; (2) HOMO-1 and LUMO+1 bands are localized in the wide units; (3) Hybridization between two units could be minimized by enforcing twist on backbone.

Towards Organic Photodetectors Functioning Under Strong Sunlight. Machine-learning-assisted Design of Diarylethene n-type Dopants to Mix with p-type Organic Semiconductor P3HT

2024-04-03T15:00:00Z

Title: Towards Organic Photodetectors Functioning Under Strong Sunlight. Machine-learning-assisted Design of Diarylethene n-type Dopants to Mix with p-type Organic Semiconductor P3HT Author(s): 안재환; 최창원; 전우진; 장윤희 Abstract: Linear dynamic range of organic photodetectors, which is typically narrow due to low mobility of organic semiconductor, has been extended by diarylethene (DAE) photochromic switches doped to a poly-3-hexylthiophene photoactive layer. A speculated mechanism is that DAE acts as n-type electron traps only in its aromatic closed form, which is predominant only under strong sunlight, addressing the early saturation problem on sunny days. We herein identified two optimal DAE derivatives out of ~100 candidates, using the TDDFT calculations on the HOMO-LUMO energies of their open-closed isomers (~400 data). Since this is only a small subset of ~105 candidates, we predicted the HOMO-LUMO energies of the remaining candidates by machine learning with various artificial neural network models and molecule representation methods. We were able to identify additional optimal candidates, which were screened by machine learning prediction, and were confirmed by TDDFT calculations.

Enhancing Stretchability of PEDOT:PSS Films with Ionic Liquid Pretreatment: A Molecular Dynamics Study

2024-09-30T15:00:00Z

Title: Enhancing Stretchability of PEDOT:PSS Films with Ionic Liquid Pretreatment: A Molecular Dynamics Study Author(s): 최창원; Lansac, Yves; 장윤희 Abstract: Poly(3,4-ethylenedioxythiophene):poly(stryrenesulfonate) (PEDOT:PSS) is the most promising material for stretchable electronic components because it is stable, transparent and solution processable. However, the pristine PEDOT:PSS thin film has limited electrical conductivity (<10 S/cm) and low yield strain (<6%). The electrical conductivity and stretchability of pristine PEDOT:PSS films can be improved by ionic liquid (IL). We investigate the effect of ILs on the PEDOT:PSS morphology through molecular dynamics simulations of the mechanical properties of PEDOT:PSS subjected to uniaxial strain. Through this, we observe at the molecular level how the morphology change by the IL can improve the stretchability of the PEDOT:PSS. Finally, the principle of improving the electrical and mechanical properties of PEDOT:PSS of the IL is identified, and the design principle of the IL is proposed to control the desired properties.

Enhancement of PEDOT:PSS Stretchability with Ionic Liquid: A Molecular Dynamics Simulation Study

2023-10-10T15:00:00Z

Title: Enhancement of PEDOT:PSS Stretchability with Ionic Liquid: A Molecular Dynamics Simulation Study Author(s): 최창원; Yves, Lansac; 장윤희 Abstract: Poly(3,4-ethylenedioxythiophene):poly(stryrenesulfonate) (PEDOT:PSS) is the most promising material for stretchable electronic components because it is stable, transparent and solution processable. However, the pristine PEDOT:PSS thin film has limited electrical conductivity (<10 S/cm) and low yield strain (<6%). In general, high crystallinity is required for conductivity, but this hinders elasticity. The electrical conductivity and elasticity of pristine PEDOT:PSS films can be improved by ionic liquid (IL). We observe the effect of IL on the PEDOT:PSS morphology through all atom molecular dynamics simulations of the mechanical properties of PEDOT:PSS subjected to uniaxial strain. We propose how IL improves the elasticity of PEDOT:PSS and a design principle of IL that can control the desired properties.