Article
Physics, Applied
Non Thongprong, Phillip M. Duxbury
Summary: A drift-diffusion bilayer interface model was developed to describe the physics of bilayer organic photovoltaics. The derived diode equation from this model shows that its parameters are voltage-dependent due to space charge accumulation. The study successfully explains common discrepancies in organic photovoltaic JV curve analyses.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Chao Wu, Weiqiang Liu, Kai Li, Gang Cheng, Jinfan Xiong, Teng Teng, Chi-Ming Che, Chuluo Yang
Summary: Intramolecular through-space charge-transfer (TSCT) excited states are utilized for developing thermally activated delayed fluorescence (TADF) emitters, with a series of precisely controlled TSCT emitters designed through alignment optimization of donor and acceptor segments. By increasing intramolecular pi-pi interactions, radiative decay rate of the lowest singlet excited state (S-1) is progressively enhanced with suppression of nonradiative decay, leading to significantly improved photoluminescence quantum yields of up to 0.99 in doped thin films. A high-efficiency electroluminescence device achieves a maximum external quantum efficiency (EQE) of 23.96% and maintains >20% at a brightness of 1000 cd m(-2), highlighting the importance of conformation control for high-efficiency intramolecular exciplex emitters.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Guosheng Li, Zhipeng Xie, Qi Wang, Xiong Chen, Yongfan Zhang, Xinchen Wang
Summary: Constructing local donor-acceptor architecture and establishing a ternary acceptor-donor-acceptor molecular junction in organic semiconductors can accelerate interface charge transfer, leading to enhanced photocatalytic performance.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Physical
Md Habibur Rahaman, Borong Sang, Md. Anower Hossain, Bram Hoex, Pablo Mota-Santiago, Valerie D. Mitchell, Ashraf Uddin, John A. Stride
Summary: Functionalization of the interface between the electron transport layer, organic polymeric donor, and non-fullerene acceptor bulk heterojunction layer in inverted structure photovoltaic devices is an effective strategy for improving performance. This study demonstrates that the interfacial nanomorphology of PTB7-Th and IEICO-4F on a bilayer of ultrathin titanium oxide (TiO2) passivated sol-gel grown zinc oxide (ZnO) electron transport layer can be improved, leading to enhanced overall organic photovoltaic device performance.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Leonardo R. Buizza, Harry C. Sansom, Adam D. Wright, Aleksander M. Ulatowski, Michael B. Johnston, Henry J. Snaith, Laura M. Herz
Summary: The study demonstrates that silver-bismuth based semiconductors exhibit good semiconductor properties, with optoelectronic properties significantly improved with increasing copper content. The presence of Cu+ enhances charge-carrier transport in the materials and reduces exciton binding energies.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Applied
Zhiyong Liu, Hongen Wang
Summary: In this study, a ternary polymer solar cell was fabricated using two well-compatible donors and one acceptor, achieving a higher power conversion efficiency. The use of two donors with similar HOMO energy levels and cascade LUMO energy levels is an efficient method to improve the performance of PSCs.
Article
Materials Science, Multidisciplinary
Di Sen Chong, Joel Jie Foo, Xin-Quan Tan, Grayson Zhi Sheng Ling, Lling-Lling Tan, Xingzhu Chen, Wee-Jun Ong
Summary: The global population growth has led to an increase in energy demand, while the rapid growth in the manufacturing and energy industries has resulted in the uncontrolled emission of harmful substances. Photocatalysis is considered as a sustainable technology to address these issues, and two-dimensional bismuth-based nanomaterials have gained attention due to their visible light absorption ability. However, the pristine materials have a high charge recombination rate, and heterojunction engineering has been proven to improve the separation efficiency of photogenerated charge carriers. Therefore, it is significant to study the synergy effect between heterojunction and morphology engineering of bismuth-based photocatalysts.
APPLIED MATERIALS TODAY
(2022)
Article
Optics
Zakir Caldiran, Sakir Aydogan
Summary: The study utilized P3HT:PCBM photoactive layers blended in different ratios and observed that the mixing ratio affected the surface morphology and absorption characteristics of the active layer, thereby impacting the device performance parameters. By evaporating a LiF layer on the active layer and optimizing device design, the power conversion efficiency of OPVs was successfully increased.
Article
Nanoscience & Nanotechnology
Fani Eirini Taifakou, Muhammad Ali, Joanna Borowiec, Xiaoqi Liu, Peter A. Finn, Christian B. Nielsen, Cozmin Timis, Tamsin Nooney, Adrian Bevan, Theo Kreouzis
Summary: Organic semiconductor diodes fabricated using a blend of poly(3-hexylthiophene) and phenyl-C-61-butyric acid methyl ester achieved consistent 4 MeV alpha particle detection. The devices showed reproducible, reversible, and repeatable alpha particle detection with low-voltage operation, reaching high confidence levels with signal-to-noise ratios exceeding 20. Optimization of device dimensions and drive conditions resulted in increased gain-efficiency products, demonstrating the viability of solution-processed organic semiconductor diodes for low-voltage alpha particle detection.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Engineering, Electrical & Electronic
Zhen Cui, Kunqi Yang, Yang Shen, Zhihao Yuan, Yanbo Dong, Pei Yuan, Enling Li
Summary: This study constructs WS2/WSSe and WSSe/WS2 bilayers using single-layer WS2 and WSSe with a lattice mismatch rate of 1.85%. The bilayers exhibit better carrier mobility and conductivity than single-layer WS2. The band structure calculations show that WS2/WSSe and WSSe/WS2 bilayers have type-II band alignment. They also exhibit redox reactions and a built-in electric field, leading to enhanced photocatalytic performance with high power conversion efficiency (PCE) of 15.5% and 15.7%, respectively. Overall, WS2/WSSe and WSSe/WS2 bilayers are promising materials for photocatalytic water splitting.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Multidisciplinary
Tianyu Huang, Qi Wang, Guoyun Meng, Lian Duan, Dongdong Zhang
Summary: This study demonstrates the successful improvement of radiative decay rates of blue TSCT-TADF emitters by adopting a xanthene bridge to construct space-confined face-to-face donor-acceptor alignment.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Hui Li, Zhen Xu, Jian Song, Haoyu Chai, Lili Wu, Lidong Chen
Summary: Chemical doping of donor-acceptor (D-A) polymers is crucial for highly efficient optoelectronic devices. A new D-A polymer, Pg(3)2T-OTz, was designed and synthesized with high carrier concentration and mobility achieved through a single-solution doping method. The research demonstrates that modulation of acceptor strength combined with side-chain engineering is an effective strategy to improve both doping efficiency and carrier transport properties of D-A polymers.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Zhuohong Xie, Woncheol Seo, Syed Taj Ud Din, Hankyu Lee, Changchang Ma, Woochul Yang
Summary: Solar-driven CO2 conversion into chemical fuels using photocatalysts is a sustainable method for renewable energy. However, the low photocatalytic activity is limited by poor photoabsorption, low charge separation efficiency, and sluggish interfacial reaction. To address this issue, a mesh cladding structure of Sr-doped LaFeO3/Bi4O5Br2 photocatalyst with abundant surface oxygen vacancies (OVs) is developed. The optimized photocatalyst with appropriate Sr doping and BOB content shows a considerable methane generation, which is significantly higher than the pristine LFO.
MATERIALS TODAY ENERGY
(2023)
Article
Chemistry, Physical
Yuljae Cho, Bo Hou, Paul Giraud, Sangyeon Pak, SeungNam Cha
Summary: Research has shown that modulating charge carrier transport at the heterojunction interface with ferroelectric materials can enhance the performance of photovoltaic devices, reduce charge recombination, and improve conversion efficiency. The coupling of the ferroelectric effect with solar cells provides an important platform for the development of solution-processable flat panel solar cell technology.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Polymer Science
Fatima Hameed, Manikandan Mohanan, Nafisa Ibrahim, Charles Ochonma, Joaquin Rodriguez-Lopez, Nagarjuna Gavvalapalli
Summary: Controlling the interaction between pi-conjugated polymer and acceptor complex is crucial in organic electronics and energy applications. Strapped pi-conjugated polymers are effective in controlling the interactions of the polymer backbone with other chains and small molecules. By synthesizing a series of copolymers containing both strapped and nonstrapped comonomers, the interactions between the polymer and acceptor can be controlled. The presence of straps leads to higher photoinduced photoluminescence quenching and improved electron transfer efficiency.
Article
Polymer Science
Hazuki Maeda, Ryo Inoue, Akinori Saeki, Yasuhiro Morisaki
Summary: The synthesis of polymers with stacked three-ring para-phenylene-ethynylene pi-electron systems through Sonogashira-Hagihara cross-coupling was successful. The optically active pseudo-meta-linked dimers and polymers emitted intense circularly polarized luminescence (CPL) with relatively high anisotropy factors.
Article
Polymer Science
Shaoxian Li, Ryosuke Nishikubo, Tatsuho Wada, Tomokazu Umeyama, Hiroshi Imahori, Akinori Saeki
Summary: This study evaluates the charge carrier dynamics in different structured organic solar cells and reveals the factors limiting the power conversion efficiency (PCE). The results show that the OSC with the highest PCE has low electron and hole mobilities, while the one with higher electron and hole mobilities has a lower PCE. Additionally, the OSC with the highest PCE exhibits the smallest bimolecular recombination coefficient.
Article
Nanoscience & Nanotechnology
Nanaki Minoi, Fumitaka Ishiwari, Kazuharu Murotani, Ryosuke Nishikubo, Takanori Fukushima, Akinori Saeki
Summary: In this study, a novel molecular concept of a C2-symmetric syn-type bifacial donor-pi-donor (D-pi-D) passivation molecule was introduced to enhance the power conversion efficiency of organic-inorganic lead halide perovskite solar cells. The experimental results showed that this molecule could effectively stabilize the surface of the solar cells, facilitate hole transfer, reduce the remnant PbI2, and change the perovskite orientation, leading to an increase in the maximum efficiency of the cells.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Shunta Nakamura, Hayato Sakai, Masaaki Fuki, Rikuto Ooie, Fumitaka Ishiwari, Akinori Saeki, Nikolai V. V. Tkachenko, Yasuhiro Kobori, Taku Hasobe
Summary: We have synthesized a series of Tc oligomers and proposed a molecular design strategy for efficient exciton transport in linear oligomers. By promoting correlated TT dissociation and controlling sequential exciton trapping process, we observed high-yield exciton trapping. The results reveal the importance of entropic effects and vibronic coupling for enhanced exciton migration.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Hajime Suzuki, Takanori Takashima, Osamu Tomita, Tomoki Kanazawa, Shunsuke Nozawa, Kosaku Kato, Akira Yamakata, Kouichi Nakashima, Akinori Saeki, Ryu Abe
Summary: In this study, a Bi6NbWO14Cl photocatalyst was synthesized using Rh(2)O(3) additives and its surface was modified with Rh species to improve its photocatalytic activity. The addition of an appropriate amount of Rh2O3 significantly enhanced the O-2 evolution rate on Bi6NbWO14Cl, likely due to enhanced charge transfer by metallic Rh nanoparticles. Surface modification with Rh species further enhanced the O-2 evolution rate, achieving an apparent quantum efficiency of 11% at 420 nm, the best reported performance for oxyhalides prepared by solid-state reactions. The roles of these Rh species in the enhanced photocatalytic activities were discussed.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Ryosuke Nishikubo, Yasutaka Kuwahara, Shintaro Naito, Kazuki Kusu, Akinori Saeki
Summary: Hydrogenated molybdenum suboxide (HxMoO3-y) is a promising material for photo-thermal energy conversion (PEC), but its charge carrier dynamics and mechanisms are not well understood. In this study, charge carrier-dielectric interactions in Pt/HxMoO3-y composite were investigated using flash-photolysis time-resolved microwave conductivity. The results showed that the charge recombination of H2-reduced Pt/HxMoO3-y was much faster than that of Pt/MoO3, indicating efficient PEC. The study also identified two trapping mechanisms, Drude-Zener (DZ) and negative permittivity effect (NPE) modes, in Pt/HxMoO3-y depending on the reduction temperature. Optimal PEC performance was achieved when Pt/HxMoO3-y was reduced at 200 degrees C, balancing the suppression of NPE and charge diffusion. This study provides the first insights into charge dynamics in hydrogenated metal oxides and their impact on PEC processes.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Ryota Akai, Kouki Oka, Shun Dekura, Kazuyoshi Yoshimi, Hatsumi Mori, Ryosuke Nishikubo, Akinori Saeki, Norimitsu Tohnai
Summary: Organic semiconductors show high charge carrier mobility due to the spread of the pi-orbital. This study investigated the direct effect of subtle differences in pi-orbital overlap on charge carrier mobility by precisely controlling molecular arrangements. The synthesized disulfonic acid with a BTBT moiety exhibited identical electronic states, but slight variations in steric hindrance, center-to-center distances, and dihedral angles resulted in different photoconductivity and theoretical charge carrier mobility from crystal structures.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Michihisa Toya, Takuya Omine, Fumitaka Ishiwari, Akinori Saeki, Hideto Ito, Kenichiro Itami
Summary: Expanded carbohelicenes fused to 15-and 17-benzenewere were synthesized using a new synthetic strategy. The sequential integration of pi-elongating Wittig reaction and ring-fusing Yamamoto coupling was utilized in the synthesis of [2,1][15]-helicenes and [2,1][17]-helicenes. The unique characteristics of the expanded helicenes were determined through X-ray crystallographic structures, photophysical properties, and density functional theory (DFT) calculations. Furthermore, optical resolution of [2,1][17]-helicene was achieved, and the chiroptical properties of enantiomers of pristine [2,1]-[n]-helicene core were elucidated for the first time.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Nanoscience & Nanotechnology
Takeyuki Sekimoto, Teruaki Yamamoto, Fumito Takeno, Ryosuke Nishikubo, Maki Hiraoka, Ryusuke Uchida, Toru Nakamura, Kenji Kawano, Akinori Saeki, Yukihiro Kaneko, Taisuke Matsui
Summary: To enhance the light stability of lead-halide perovskite solar cells, a self-assembled monolayer (SAM) is introduced between the carrier transport layer and the perovskite layer. By combining a fullerene-functionalized SAM (C(60)SAM) and a suitable gap-filling SAM (GFSAM), both the photovoltaic conversion efficiency (PCE) and light stability are improved. The best cell with C(60)SAM and GFSAM exhibits a PCE of 18.68% and a retention rate of over 99% after a light stability test, and shows almost unchanged PCE after six months of outdoor exposure.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Fengniu Lu, Akira Shinohara, Izuru Kawamura, Akinori Saeki, Tomohisa Takaya, Koichi Iwata, Takashi Nakanishi
Summary: This paper presents the room-temperature liquefaction of diphenylpyrene isomers by introducing bulky yet flexible branched alkyl chains through molecular desymmetrization. Six isomers with different symmetries were synthesized, and three of them were found to be liquids at 25°C and have remained in this state for more than five years. The unexpectedly non-crystallizing molecule with relatively high molecular symmetry was confirmed by rheological analysis of the amorphous material's kinetic inhomogeneity.
HELVETICA CHIMICA ACTA
(2023)
Article
Materials Science, Multidisciplinary
Masahiko Saito, Hiroya Yamada, Kakaraparthi Kranthiraja, Tsubasa Mikie, Akinori Saeki, Hideo Ohkita, Itaru Osaka
Summary: In this study, a benzodithiophene-thiazolothiazole copolymer with tripropylsilyl groups (PSTz2) was found to have a larger coplanar backbone structure in solutions and blended films with nonfullerene acceptors, compared to its crystalline state. The excitons and charge carriers in PSTz2 were more easily delocalized in the blend films, potentially through the backbone. This unconventional structural feature resulted in higher photovoltaic performance in nonfullerene-based solar cells compared to its alkyl-functionalized counterpart.
COMMUNICATIONS MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Ravindra Kumar Gupta, Manabu Yoshida, Akinori Saeki, Zhenfeng Guo, Takashi Nakanishi
Summary: Special attention is being given to the potential use of soft electronics in deformable/wearable devices, and electrets are expected to be a battery-less power source. This study presents a strategy for utilizing charges in alkyl-C-60 liquids. The alkyl-C-60 liquids with bulky long-alkyl chains demonstrated good charge retention and were used to fabricate deformable mechanoelectric generator (MEG) devices, showing promising potential for body motion sensors and healthcare applications.
MATERIALS HORIZONS
(2023)
Article
Chemistry, Physical
Hajime Suzuki, Daichi Ozaki, Yusuke Ishii, Osamu Tomita, Daichi Kato, Shunsuke Nozawa, Kouichi Nakashima, Akinori Saeki, Hiroshi Kageyama, Ryu Abe
Summary: Bismuth-based oxyhalides with layered Sillen(-Aurivillius) structures have been studied as photocatalysts. A Sillen-type oxyhalide, SrBi3O4Cl3, showed visible light response up to 460 nm, attributed to the asymmetric Bi occupation and the coexistence of halogen layers. This study also revealed the spatial separation of the conduction band minimum and valence band maximum in SrBi3O4Cl3, which promotes charge carrier separation and facilitates visible-light-driven water splitting.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Yasuhito Kobayashi, Yuta Miyake, Fumitaka Ishiwari, Shintaro Ishiwata, Akinori Saeki
Summary: The bulk heterojunction structures of organic photovoltaics (OPVs) have been overlooked in their machine learning (ML) approach despite their presumably significant impact on power conversion efficiency (PCE). In this study, we examined the use of atomic force microscopy (AFM) images to construct an ML model for predicting the PCE of polymer : non-fullerene molecular acceptor OPVs. The accuracy of the model did not considerably improve even by including AFM data in addition to the chemical structure fingerprints, material properties and process parameters. However, we found that a specific spatial wavelength of FFT (40-65 nm) significantly affects PCE. The GLCM and HA methods, such as homogeneity, correlation and skewness expand the scope of image analysis and artificial intelligence in materials science research fields.
Article
Chemistry, Multidisciplinary
Ryohei Akiyoshi, Akinori Saeki, Kazuyoshi Ogasawara, Hirofumi Yoshikawa, Yuiga Nakamura, Daisuke Tanaka
Summary: Two-dimensional Ag(i) coordination polymers with a sulfur coordination atom, KGF-24 and KGF-25, were synthesized and characterized. Time-resolved microwave conductivity measurements and first-principles calculations showed that they exhibit charge mobility along their (-Ag-S-)(n) network.
