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End-Group Alkylation of Diarylethene to Enhance Photo-Switchability of Organic Transistors
Syed Zahid Hassan,유성훈,소찬,문도현,정대성 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
A molecular and synthetic approach to strengthen switching performance of diarylethene (DAE)-based organic transistor is proposed. From photophysical, structural and morphological analyses, we found that longer alkyl chains inhibit intermolecular aggregation between DAEs and allow more hydrophobic surface property of DAEs, thus improving molecular miscibility with ITIC. In addition, it is found that the improved molecular compatibility of DAEs with ITIC makes the overall bulk heterojunction (BHJ) film amorphous, allowing more free volume for reversible photoisomerization. As a result, DAE_C6 exhibits the maximum quantum yield for both photocyclization and photocycloreversion, enabling high light-controlled on/off ratios when employed as a photoswitch of ITIC transistor. Furthermore, exceptionally high quantum yield of DAE_C6 enables robust fatigue resistance under repeated photoswitching of the transistor with only 30% decrease of on/off ratio after 100 cycles.
Hassan, Syed Tauseef,Danish, Danish,khan, Salah-Ud-Din,Baloch, Muhammad Awais,Tarar, Zahid Hassan Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12
Looking at the recent studies, nuclear energy and carbon dioxide (CO<sub>2</sub>) emissions nexus shows inconclusive result. To further explain nuclear energy-pollution nexuses this study is an attempt to analyze the impact of nuclear energy on pollution reduction for BRICS countries covering data for the period from 1993 to 2017. This study conducts advanced panel techniques such as Continuously-Updated Fully-Modified (CUP-FM) and Continuously-Updated Bias-Corrected (CUP-BC) for long run estimation. Our results support the notion that nuclear energy reduce CO<sub>2</sub> emissions. Also, renewable energy corrects environmental pollution in BRICS countries. The magnitude of the coefficient of nuclear energy is less as compared to renewable energy, implying that nuclear is less effective in reducing environmental pollution. The findings offer significant policy understandings and suggestions not only for BRICS economies but for developing countries as well in designing suitable nuclear energy-growth-carbon policies.
Hassan, Syed Zahid,Cheon, Hyung Jin,Choi, Changwon,Yoon, Seongwon,Kang, Mingyun,Cho, Jangwhan,Jang, Yun Hee,Kwon, Soon-Ki,Chung, Dae Sung,Kim, Yun-Hi American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.31
<P>Herein, we explore the strategy of realizing a red-selective thin-film organic photodiode (OPD) by synthesizing a new copolymer with a highly selective red-absorption feature. PCZ-Th-DPP, with phenanthrocarbazole (PCZ) and diketopyrrolopyrrole (DPP) as donor and acceptor units, respectively, was strategically designed/synthesized based on a time-dependent density functional theory calculation, which predicted the significant suppression of the band II absorption of PCZ-Th-DPP due to the extremely efficient intramolecular charge transfer. We demonstrate that the synthesized PCZ-Th-DPP exhibits not only a high absorption coefficient within the red-selective band I region, as theoretically predicted, but also a preferential face-on intermolecular structure in the thin-film state, which is beneficial for vertical charge extraction as an outcome of a glancing incidence X-ray diffraction study. By employing PCZ-Th-DPP as a photoactive layer of Schottky OPD, to fully match its absorption characteristic to the spectral response of the red-selective OPD, we demonstrate a genuine red-selective specific detectivity in the order of 10<SUP>12</SUP> Jones while maintaining a thin active layer thickness of ∼300 nm. This work demonstrates the possibility of realizing a full color image sensor with a synthetic approach to the constituting active layers without optical manipulation.</P> [FIG OMISSION]</BR>
유성훈,Syed Zahid Hassan,안상혁,강보석,정대성 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
The key issue of next-generation semiconducting devices is to amplify the functionality of each device without compromising the physical dimensions, and in this case, photochromic molecular switches can have many uses. The most reliable and useful method for forming a photochromic molecular switch is to control the work function of the noble metal using light with the aid of self-assembled monolayers (SAMs). The physical and chemical analyses of the SAM formation using molecules with long alkyl chains have been conducted for a long time, and the optimal processing method for each molecule is well established. However, the guidelines for SAMs used as photochromic molecular switches are still insufficient. Here, we present a general guideline for the preparation of SAMs for the optimal operation of photochromic molecular switches. The influence of the processing solvent on the switching performance of a fluorinated azobenzene based-transistor is carefully analyzed.