26 Apr 11:29
by Rui Sun,
Yao Wu,
Xinrong Yang,
Yuan Gao,
Zeng Chen,
Kai Li,
Jiawei Qiao,
Tao Wang,
Jing Guo,
Chao Liu,
Xiaotao Hao,
Haiming Zhu,
Jie Min
A new ternary system is developed by introducing an asymmetric electron acceptor BTP-2F2Cl into the PM1:L8-BO host system. The ternary system exhibits a record-high efficiency of 19.17% and demonstrates better long-term stability compared to the host system.
Abstract
The ternary strategy has been widely identified as an effective approach to obtain high-efficiency organic solar cells (OSCs). However, for most ternary OSCs, the nonradiative voltage loss lies between those of the two binary devices, which limits further efficiency improvements. Herein, an asymmetric guest acceptor BTP-2F2Cl is designed and incorporated into a PM1:L8-BO host blend. Compared with the L8-BO neat film, the L8-BO:BTP-2F2Cl blend film shows higher photoluminescence quantum yield and larger exciton diffusion length. Introducing BTP-2F2Cl into the host blend extends its absorption spectrum, improves the molecular packing of host materials, and suppresses the nonradiative charge recombination of the ternary OSCs. Consequently, the power conversion efficiency is improved up to 19.17% (certified value 18.7%), which represents the highest efficiency value reported for single-junction OSCs so far. The results show that improving the exciton behaviors is a promising approach to reducing the nonradiative voltage loss and realizing high-performance OSCs.
26 Apr 02:01
by Qigang Zhong, Kaifeng Niu, Long Chen, Haiming Zhang, Daniel Ebeling, Jonas Björk, Klaus Müllen, André Schirmeisen, and Lifeng Chi
Journal of the American Chemical Society
DOI: 10.1021/jacs.2c01338
16 Apr 07:19
by Kai-Hua Kuo, Richie Estrada, Chih-Chien Lee, Nurul Ridho Al Amin, Ya-Ze Li, Marvin Yonathan Hadiyanto, Shun-Wei Liu, and Ken-Tsung Wong
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.2c04434
16 Apr 07:19
by Ke Yang, Fei Long, Wei Liu, Zequn Zhang, Shaojing Zhao, Benhua Wang, Yingping Zou, Minhuan Lan, Jun Yuan, Xiangzhi Song, and Changwei Lin
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.1c22444
12 Apr 12:09
by Shakil N. Afraj,
Chia‐Chi Lin,
Arulmozhi Velusamy,
Chang‐Hui Cho,
Hsin‐Yi Liu,
Jianhua Chen,
Gene‐Hsiang Lee,
Jui‐Chen Fu,
Jen‐Shyang Ni,
Shih‐Huang Tung,
Shuehlin Yau,
Cheng‐Liang Liu,
Ming‐Chou Chen,
Antonio Facchetti
The effect of heteroalkyl (-XR, X = O, S, Se) substitution on a series of small molecule semiconductors having a 3,3′-diheteroalkyl-2,2′-bithiophene central cores are studied. Solution-processed DDTT-SeBT (1) organic field effect transistors exhibit high hole mobility of 4.01 cm2 V−1 s−1, far surpassing those of the corresponding SBT and OBT compounds.
Abstract
The effect of heteroalkyl (-XR, X = Se, S, O) substitution on a series of molecular semiconductors having a 3,3′-diheteroalkyl-2,2′-bithiophene (XBT) central core is studied. Thus, the selenotetradecyl (-SeC14H29) SeBT core is investigated by end-functionalization with two dithienothiophene (DTT), thienothiophene (TT), and thiophene (T) units to give SeBTs 1–3, respectively, for molecular π-conjugation effect examination. Furthermore, the selenodecyl (-SeC10H21) and selenohexyl (-SeC6H13) SeBT cores end-capped with DTTs to give SeBTs 1B and 1C, respectively, are synthesized for understanding -SeR length effects. To address systematically the impact of the chalcogen heteroatom, the newly developed selenoalkyl SeBTs are compared with the previously reported thiotetradecyl (-SC14H29) DDTT-SBT (4) and the new tetradecyloxy (-OC14H29) DDTT-OBT (5). When fabricating organic field effect transistors by the solution-shearing method, the devices based on the tetradecylated DDTT-SeBT (1) exhibit the highest mobility up to 4.01 cm2 V−1 s−1, which is larger than those of the other SeBT compounds and both DDTT-SBT (4) (1.70 cm2 V−1 s−1) and DDTT-OBT (5) (9.32 × 10−4 cm2 V−1 s−1). These results are rationalized by a combination of crystallographic, morphological, and microstructural analysis.
12 Apr 12:09
by Ziting Zhong,
Xiangyu Zhu,
Xianhui Wang,
Yu Zheng,
Sinuo Geng,
Zhikuan Zhou,
Xin Jiang Feng,
Zujin Zhao,
Hua Lu
High steric-hindrance windmill-type molecules with different donors and conjugation lengths emitting from UV to pure-blue are designed. The doped devices of these dyes exhibit excellent electroluminescence performances by harvesting triplet excitons via the hybridized local and charge-transfer excited state. An efficient UV device is achieved, providing an external quantum efficiency of 7.9% and CIEy of 0.04.
Abstract
Hybridized local and charge-transfer (HLCT) excited-state compounds that enable full exciton utilization through a reverse intersystem conversion (RISC) from a high-lying triplet to a singlet state have attracted attention. Developing high-performance ultraviolet (UV) and blue organic light-emitting diodes (OLEDs) is challenging due to difficulties acquiring HLCT molecules with a large energy bandgap and a high photoluminescence. Herein, a new strategy for excellent-performance UV to blue emitters based on high steric-hindrance windmill-type structure is proposed. These emitters exhibit good thermal, morphological, and electrochemical stabilities, as well as HLCT excited-state characteristics. Results suggest that OLED using CTPPI efficiently emits UV light (396 nm, CIEx,y = 0.16, 0.04) with a maximum external quantum efficiency (EQE) of 7.9% and currently ranks third in UV OLEDs. The lights of these devices are well modulated from UV/deep-blue to pure-blue with EQEs greater than 5% by regulating the locally excited (LE) and charge-transfer (CT) components. Experimental and theoretical investigations indicate that harvesting triplet excitons afford high electroluminescence efficiencies via HLCT excited states in the devices. This study provides an efficient strategy to achieve high-performance UV and blue OLEDs and offers great flexibility for material design.
12 Apr 10:50
by Tae Hyuk Kim,
Ho Jin Lee,
Muhammad Ahsan Saeed,
Jae Hoon Son,
Han Young Woo,
Tae Geun Kim,
Jae Won Shim
In this study, performance degradation factors of organic photovoltaics (OPVs) under indoor stress are unveiled. Morphological evolution and molecular packing variation are deeply investigated. Indoor stability enhancement is achieved with increasing photoactive components. The quaternary OPVs show great performance retention under viable indoor stresses.
Abstract
Despite recent improvements in their power-conversion efficiency (PCE), organic photovoltaics (OPVs) cannot yet be guaranteed stable in an indoor environment. In this study, the destabilizing effects of morphological evolution and molecular-ordering variation on photoactive layers containing two to four photoactive components are investigated under realistic indoor photothermal (>55 °C for 1000 h) and mechanical (10% strain and 1000 cycles) deformation conditions. Layers with more stable morphologies are obtained by increasing the number of photoactive components; consequently, the quaternary OPVs show the best PCE retention (over 90% and 82% of the initial values after the photothermal and mechanical stresses, respectively). The increase in entropy caused by the additional components in the quaternary blend leads to a more balanced molecular arrangement and excellent photothermal stability. Stronger intermolecular bonding and less variation of molecular ordering likewise occur in the quaternary OPVs, enhancing their mechanical endurance.
12 Apr 10:33
by Junseop Lim,
Si Hyun Han,
Jun Yeob Lee
White organic light-emitting diodes are developed using highly efficient and long range charge transfer complex emission between two blue phosphorescent emitters induced by an electric field.
Abstract
Herein, the authors report on charge-transfer (CT) complex emission-based organic light-emitting diodes (OLEDs), which emit light by electric field-induced intermolecular CT complex formation in the light-emitting layer. Two phosphorescent materials are chosen to have energy level offset for the CT complex formation. This process generates the CT complex, which efficiently emits only in the electroluminescent device by electric-field-induced complex formation. A phenylpyridine-ligand-based Ir compound and phenylimidazole-based Ir compounds are selected as the CT complex-forming materials, and the CT complex exhibits yellow emission under an electric field. Moreover, the doping of the two compounds in the host material produces white OLEDs, exhibiting both blue emission and yellow emission at a quantum efficiency of 13.7%. In particular, the color of the CT complex device can be tuned by the content of each material in the emitting layer. As an initial result, the quantum efficiency is acceptable, and further material development would enhance the quantum efficiency of the CT complex OLEDs. This light-emitting device can be used in various applications, e.g., a mono-color or a white-color light-emitting diode.
12 Apr 10:32
by Matthias Diethelm,
Michael Bauer,
Wei‐Hsu Hu,
Camilla Vael,
Sandra Jenatsch,
Paul W. M. Blom,
Frank Nüesch,
Roland Hany
The filling of deep electron traps for a range of polymer-based light-emitting diodes needs many minutes, in contrast to the general notion that trap filling is completed after hundreds of microseconds. This remarkable appearance is consistent with a slow diffusion process between precursor trap species that form a trap only while meeting with the hydrated oxygen complex as a possible candidate.
Abstract
Semiconducting polymers are being studied intensively for optoelectronic device applications, including solution-processed light-emitting diodes (PLEDs). Charge traps in polymers limit the charge transport and thus the PLED efficiency. It is firmly established that electron transport is hindered by the presence of the universal electron trap density, whereas hole trap formation governs the long-term degradation of PLEDs. Here, the response of PLEDs to electrical driving and breaks covering the timescale from microseconds to (a few) hours is studied, thus focusing on electron traps. As reference polymer, a phenyl-substituted poly(para-phenylene vinylene) (PPV) copolymer termed super yellow (SY) is used. Three different traps with depths between ≈0.4 and 0.7 eV, and a total trap site density of ≈2 × 1017 cm−3 are identified. Surprisingly, filling of deep traps takes minutes to hours, at odds with the common notion that charge trapping is complete after a few hundred microseconds. The slow trap filling feature for PLEDs is confirmed using poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV) and poly(3-hexylthiophene) (P3HT) as active materials. This unusual phenomenon is explained with trap deactivation upon detrapping and slow trap reactivation. The results provide useful insight to pinpoint the chemical nature of the universal electron traps in semiconducting polymers.
08 Apr 14:00
J. Mater. Chem. C, 2022, 10,4748-4756
DOI: 10.1039/D1TC04700K, Paper
Yi-Tzu Hung, Dian Luo, Li-Ming Chen, Dun-Cheng Huang, Jian-Zhi Wu, Yi-Sheng Chen, Chih-Hao Chang, Ken-Tsung Wong
Two bipolar molecules CzT2.1 and CzT2.2 are examined as electron acceptors to form exciplexes with electron donors 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 4,4′,4′′-tris(carbazol-9-yl)-triphenylamine (TCTA), respectively.
The content of this RSS Feed (c) The Royal Society of Chemistry
08 Apr 13:59
J. Mater. Chem. C, 2022, 10,4723-4736
DOI: 10.1039/D1TC04656J, Paper
Yuzhi Song, Bihe Li, Songsong Liu, Ming Qin, Yang Gao, Kai Zhang, Lili Lin, Chuan-Kui Wang, Jianzhong Fan
Blue-efficient thermally-activated delayed fluorescence emitters are widely desired in organic light-emitting diodes due to their advantages in both improving display resolution and providing better pixels.
The content of this RSS Feed (c) The Royal Society of Chemistry
07 Apr 05:27
by Siqi Liu,
Haojie Li,
Xueting Wu,
Dong Chen,
Lin Zhang,
Xiangchuan Meng,
Licheng Tan,
Xiaotian Hu,
Yiwang Chen
The pseudo-planar heterojunction strategy is an efficient strategy to improving average visible transmittance (AVT) and power conversion efficiency (PCE) values of semitransparent organic solar cells (ST-OSCs) simultaneously due to the reduction of the optical loss, and the semitransparent devices afford a highest efficiency of 14.62% with a considerable AVT of 20.42%.
Abstract
The existing conformation of the active layer is defective for employment of semitransparent organic solar cells (ST-OSCs) in solar windows. Herein, scalable solar windows are successfully printed by introducing a pseudo-planar heterojunction (PPHJ) structure. The PPHJ structure can effectively improve the average visible transmittance (AVT) value while boosting the power conversion efficiency (PCE) of semitransparent devices due to the reduced optical loss. The universality of the PPHJ structure in the preparation of ST-OSCs is proved. Furthermore, an inset of a superhydrophobic patterned soft insertion layer (PSIL) in the encapsulated window improves the waterproof performance without losing transparency. Accordingly, the semitransparent devices based on the 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6) system afford a maximal efficiency of 14.62%, with a considerable AVT of 20.42%, and the resultant solar windows achieve a stabilized efficiency of 13.34% with excellent waterproof performance. Moreover, the PCE of the unilateral broken solar windows retains 70.6% of the initial efficiency after being placed under simulated rainfall conditions for 1200 h at room temperature.
07 Apr 05:23
by Liuxiao Li, Qinbai Yun, Chongzhi Zhu, Guan Sheng, Jun Guo, Bo Chen, Meiting Zhao, Zhicheng Zhang, Zhuangchai Lai, Xiao Zhang, Yongwu Peng, Yihan Zhu, and Hua Zhang
Journal of the American Chemical Society
DOI: 10.1021/jacs.2c01199
07 Apr 05:22
by Nicole Mertes, Marvin Busch, Magnus-Carsten Huppertz, Christina Nicole Hacker, Jonas Wilhelm, Clara-Marie Gürth, Stefanie Kühn, Julien Hiblot, Birgit Koch, and Kai Johnsson
Journal of the American Chemical Society
DOI: 10.1021/jacs.2c01465
30 Mar 18:35
Energy Environ. Sci., 2022, 15,2011-2020
DOI: 10.1039/D2EE00430E, Paper
Xiaolei Kong, Can Zhu, Jinyuan Zhang, Lei Meng, Shucheng Qin, Jianqi Zhang, Jing Li, Zhixiang Wei, Yongfang Li
Two isomeric A–DA′D–A type SMAs o-TEH and m-TEH were designed and synthesized, and the PCE of the OSC based on PBQ6:m-TEH reached 18.51%.
The content of this RSS Feed (c) The Royal Society of Chemistry
30 Mar 18:34
by Xianfeng Qiao,
Hui Liu,
Shu Xiao,
Peisen Yuan,
Jingwen Yao,
Yuwen Chen,
Ping Lu,
Dongge Ma
Three vibrational emission peaks of the first excited triplet state T
1 are identified in triplet–triplet annihilation (TTA) molecules at room temperature. Compared with its high-energy counterpart, the low-energy vibrational T
1 is more likely to localize and acts as an energy-loss state; thus, this state makes only slight contributions to the TTA-based upconversion process.
Abstract
Triplet–triplet annihilation (TTA) is a feasible approach for utilizing electrically generated triplet excitons in organic light-emitting diodes. However, low TTA efficiency is often observed in solids. Owing to the optically inaccessible nature of triplets, the main loss routes of the TTA process remain unknown. In this work, three vibrational emission peaks of the first excited triplet state (T
1) are identified in the sensitized room-temperature phosphorescence of TTA molecules. These peaks provide strong evidence of the loss channels of TTA. It is found that the monomolecular recombination of T
1 represents an energy-loss channel that combines the transient photoluminescence of both upconversion fluorescence and phosphorescence. Moreover, the study demonstrates that low-energy vibrational T
1 acts as an energy-loss channel with only slight contributions to TTA. This work presents constructive insights into the improvement of TTA efficiency in solid films.
30 Mar 18:34
by Chia‐Chi Lin,
Arulmozhi Velusamy,
Shih‐Huang Tung,
Itaru Osaka,
Ming‐Chou Chen,
Cheng‐Liang Liu
Photoelectric characteristics of n-type semiconducting N2200 polymer:TIIQ small molecule blend films are investigated for red light sensing phototransistors. The controlled compositions in the blend photoactive layer of phototransistors offer the photoresponsivity of 4065 A W–1, specific detectivity of 1.4 × 1013 Jones, and high mobility of 1.59 cm2 V–1 s–1.
Abstract
Semiconducting blend heterostructures, composed of conjugated polymer with photoresponsive organic crystals, provide an effective way to achieve promising photodetection devices. Here, solution-processed n-type N2200 conjugated polymer and quinoidal thienoisoindigo (TIIQ) small molecule blend is used to construct phototransistors for red light detection. The device performance of the optically switchable phototransistors can be tuned by the relative composition in the blend. The key feature is red light (680 nm) illuminated intensity-tunable photodetection enabling the highest photoresponsivity (R) of 4065 A W-1 and specific photodetectivity (D*
) of 1.4 × 1013 Jones for an 88% blend device. At the same time, maintaining high mobility (μ) of 1.59 cm2 V-1 s-1, since the efficient extraction of photogenerated charges from blend heterointerface, benefiting from blending with higher μ and enhanced absorption of TIIQ, contributes to improvement in the red light photoresponse of the N2200:TIIQ blend phototransistor. This work demonstrates that the semiconducting blend strategies provide opportunities for developing high performance organic phototransistors.
27 Mar 10:47
by Dan Liu,
Xianxin Wu,
Can Gao,
Chenguang Li,
yingshuang Zheng,
Yang Li,
Ziyi Xie,
Deyang Ji,
Xinfeng Liu,
Xiaotao Zhang,
Liqiang Li,
Qian Peng,
Wenping Hu,
Huanli Dong
An organic semiconductor, 2,7-di(2-naphthyl)-9H-fluorene (LD-2) was designed and synthesized. Comprehensive characterizations demonstrate that LD-2 combines the properties of high charge carrier mobility of 2.7 cm2 V−1 s−1 and superior lasing characteristics (low threshold of E
th=9.43 μJ cm−2 and E
th=9.93 μJ cm−2 at the peaks of 420 nm and 443 nm), which demonstrates promising potential for integrated optoelectronic device applications.
Abstract
Integrating high charge-carrier mobility and low-threshold lasing action in an organic semiconductor is crucial for the realization of an electrically pumped laser, but remains a great challenge. Herein, we present an organic semiconductor, named as 2,7-di(2-naphthyl)-9H-fluorene (LD-2), which shows an unexpected high charge-carrier mobility of 2.7 cm2 V−1 s−1 and low-threshold lasing characteristic of 9.43 μJ cm−2 and 9.93 μJ cm−2 and high-quality factor (Q) of 2131 and 1684 at emission peaks of 420 and 443 nm, respectively. Detailed theoretical calculations and photophysical data analysis demonstrate that a large intermolecular transfer integral of 10.36–45.16 meV together with a fast radiative transition rate of 8.0×108 s−1 are responsible for the achievement of the superior integrated optoelectronic properties in the LD-2 crystal. These optoelectronic performances of LD-2 are among the highest reported low-threshold lasing organic semiconductors with efficient charge transport, suggesting its promise for research of electrically pumped organic lasers (EPOLs).
27 Mar 10:45
by Zhaoyang Yao,
Fuguo Zhang,
Lanlan He,
Xingqi Bi,
Yaxiao Guo,
Yu Guo,
Linqin Wang,
Xiangjian Wan,
Yongsheng Chen,
Licheng Sun
A new class of polymeric hole-transport materials (HTMs) was explored, featuring fluorine-substituted pyrene and specific Pb−Se secondary interactions. Perovskite solar cells (PSCs) using PE10 as dopant-free HTM, afforded an excellent PCE of 22.3 %, positioning it among the best PSCs based on dopant-free HTMs.
Abstract
A new class of polymeric hole-transport materials (HTMs) are explored by inserting a two-dimensionally conjugated fluoro-substituted pyrene into thiophene and selenophene polymeric chains. The broad conjugated plane of pyrene and “Lewis soft” selenium atoms not only enhance the π–π stacking of HTM molecules greatly but also render a strong interaction with the perovskite surface, leading to an efficient charge transport/transfer in both the HTM layer and the perovskite/HTM interface. Note that fluorine substitution adjacent to pyrene boosts the stacking of HTMs towards a more favorable face-on orientation, further facilitating the efficient charge transport. As a result, perovskite solar cells (PSCs) employing PE10 as dopant-free HTM afford an excellent efficiency of 22.3 % and the dramatically enhanced device longevity, qualifying it among the best PSCs based on dopant-free HTMs.
K-Y, 以昇陳 and one other like this
27 Mar 10:43
by Hui Liu,
Ziqing Hu,
Hanwei Zhang,
Qingyun Li,
Kai Lou,
Xiaofan Ji
Through introducing fluorophores based on aggregation-induced ratiometric emission into supramolecular monomers, the molecular weight and fluorescence color of supramolecular polymers can be linked. In this system, with the increasing molecular weight, the fluorescence color changed from dark blue to yellow-green concurrently, thus enabling the visual differentiation of the molecular weight of supramolecular polymers.
Abstract
Molecular weight has an important bearing on the properties of supramolecular polymers. However, the intuitive differentiation of the molecular weight of supramolecular polymers remains challenging. Given this situation, establishing a reliable relationship between fluorescence properties and molecular weight may be a promising strategy. Herein, we prepared a supramolecular monomer M1 with aggregation-induced ratiometric emission characteristics. With the increasing M1 concentration (0.100–100 mM), the average degree of polymerization (DPDOSY) rose from 1.00 to 293. Meanwhile, the color changed from dark blue to cyan, finally to yellow-green in the same concentration range. Hence, the intuitive relationship between DPDOSY and fluorescence colors was constructed, allowing the visual differentiation of molecular weight. Moreover, the fluorescence color could be regulated by introducing a competitive molecule to induce the depolymerization of supramolecular polymers.
27 Mar 10:41
by Jinho Park,
Ki Ju Kim,
Junseop Lim,
Taekyung Kim,
Jun Yeob Lee
Optimized tandem device of the multi-resonance type blue emitter achieves high external quantum efficiency over 25% and extremely long device lifetime of over 500 h at 1000 cd m−2 and 30000 h at 100 cd m−2 up to 95% of initial luminance.
Abstract
In this study, a multiple resonance (MR) type blue emitter is synthesized, characterized, and evaluated for highly efficient and stable blue fluorescent organic light-emitting diodes (OLEDs). The MR blue fluorescent emitter has a di-tert-butyl benzene substituent in the MR core structure to minimize quenching mechanisms by intermolecular interaction. The emitter shows a high photoluminescence quantum yield and small full width at half maximum of 22 nm, which realize high external quantum efficiency (EQE) of 11.4% in the single unit OLED and device lifetime up to 95% of the initial luminance (LT95) of 208 h at 1000 cd m−2 and over 10 000 h at 100 cd m−2. The optimized tandem device of the new blue emitter achieves high EQE over 25% and extremely long LT95 of over 500 h at 1000 cd m−2 and 30 000 h at 100 cd m−2. The lifetime of this work is one of the best data of blue OLED lifetime reported in the literature.
27 Mar 10:34
by Kane T. McQuaid, Shuntaro Takahashi, Lena Baumgaertner, David J. Cardin, Neil G. Paterson, James P. Hall, Naoki Sugimoto, and Christine J. Cardin
Journal of the American Chemical Society
DOI: 10.1021/jacs.2c00178
27 Mar 10:33
by Shuyang Zhang, Maren Pink, Tobias Junghoefer, Wenchao Zhao, Sheng-Ning Hsu, Suchada Rajca, Arrigo Calzolari, Bryan W. Boudouris, Maria Benedetta Casu, and Andrzej Rajca
Journal of the American Chemical Society
DOI: 10.1021/jacs.2c01141
24 Mar 04:20
by Markus Lunzer, Joseph S. Beckwith, Franziska Chalupa-Gantner, Arnulf Rosspeintner, Giuseppe Licari, Wolfgang Steiger, Christian Hametner, Robert Liska, Johannes Fröhlich, Eric Vauthey, Aleksandr Ovsianikov, and Brigitte Holzer
Chemistry of Materials
DOI: 10.1021/acs.chemmater.1c04002
22 Mar 05:42
by Seung Soo Kim,
Soo Kyeom Yong,
Whayoung Kim,
Sukin Kang,
Hyeon Woo Park,
Kyung Jean Yoon,
Dong Sun Sheen,
Seho Lee,
Cheol Seong Hwang
V-NAND flash memory, regarding charge-trap materials (polycrystalline Si vs Si3N4−
x
), cell array architecture (NOR vs NAND), device configuration (2D vs 3D), and multilevel cell technologies is reviewed. Ways to overcome current challenges in materials and process technologies for 3D V-NAND are also suggested.
Abstract
Vertically integrated NAND (V-NAND) flash memory is the main data storage in modern handheld electronic devices, widening its share even in the data centers where installation and operation costs are critical. While the conventional scaling rule has been applied down to the design rule of ≈15 nm (year 2013), the current method of increasing device density is stacking up layers. Currently, 176-layer-stacked V-NAND flash memory is available on the market. Nonetheless, increasing the layers invokes several challenges, such as film stress management and deep contact hole etching. Also, there should be an upper bound for the attainable stacking layers (400–500) due to the total allowable chip thickness, which will be reached within 6–7 years. This review summarizes the current status and critical challenges of charge-trap-based flash memory devices, with a focus on the material (floating-gate vs charge-trap-layer), array-level circuit architecture (NOR vs NAND), physical integration structure (2D vs 3D), and cell-level programming technique (single vs multiple levels). Current efforts to improve fabrication processes and device performances using new materials are also introduced. The review suggests directions for future storage devices based on the ionic mechanism, which may overcome the inherent problems of flash memory devices.
22 Mar 05:39
by Yi Yuan,
Zhe Feng,
Shengliang Li,
Zhongming Huang,
Yingpeng Wan,
Chen Cao,
Sien Lin,
Lan Wu,
Jing Zhou,
Liang‐Sheng Liao,
Jun Qian,
Chun‐Sing Lee
An atom-programming on semiconducting oligomers tunes NIR-II emission beyond 1500 nm with high brightness. With this strategy, whole-body vessel, biliary tract, and bladder of living mice are clearly monitored at emission wavelengths over 1500 nm. Utilizing NIR-II nanoparticles, NIR-II microscopic imaging of in vivo deep-brain at a high depth of 870 µm and ultrafast hemodynamics are achieved in high resolution.
Abstract
Materials with long-wavelength second near-infrared (NIR-II) emission are highly desired for in vivo dynamic visualizating of microstructures in deep tissues. Herein, by employing an atom-programming strategy, a series of highly fluorescent semiconducting oligomers (SOMs) with tunable NIR-IIb emissions are developed for bioimaging applications. After self-assembly into nanoparticles (NPs), they show good brightness, high photostability, and satisfactory biocompatibility. The SOM NPs are applied as probes for high-resolution imaging of whole-body and hind-limb blood vessels, biliary tract, and bladder with their emissions over 1500 nm. This work demonstrates an atom-programming strategy for constructing semiconducting small molecules with enhanced NIR-II fluorescence for deep-tissue imaging, affording new insight for advancing molecular design of NIR-II fluorophores.
19 Mar 18:34
by Jingyao Chen, Xiaoxiao Xiao, Shuai Li, Yuai Duan, Guo Wang, Yi Liao, Qian Peng, Hongbing Fu, Hua Geng, and Zhigang Shuai
The Journal of Physical Chemistry Letters
DOI: 10.1021/acs.jpclett.2c00224
19 Mar 18:32
by Songming Cai, Peihao Huang, Guilong Cai, Xinhui Lu, Dingqin Hu, Chao Hu, and Shirong Lu
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.1c24017
19 Mar 11:03
J. Mater. Chem. C, 2022, 10,7866-7874
DOI: 10.1039/D1TC06165H, Paper
Jing-Wei Huang, Yu-Chieh Hsu, Xiugang Wu, Sai Wang, Xiang-Qin Gan, Wei-Qiong Zheng, Hu Zhang, Yin-Zhi Gong, Wen-Yi Hung, Pi-Tai Chou, Weiguo Zhu
Tuning the acceptor–donor assembly strategy, which is to lock the benzophenone acceptor and stepwise change the donors, demonstrates that charge transfer dominates the full width at half maximum of the multiple resonance (MR) emitters.
The content of this RSS Feed (c) The Royal Society of Chemistry
19 Mar 09:54
by Duo Li,
Shangfeng Liu,
Zeyuan Qian,
Quanfeng Liu,
Kang Zhou,
Dandan Liu,
Shanshan Sheng,
Bowen Sheng,
Fang Liu,
Zhaoying Chen,
Ping Wang,
Tao Wang,
Xin Rong,
Renchun Tao,
Jianbin Kang,
Feiliang Chen,
Junjie Kang,
Ye Yuan,
Qi Wang,
Ming Sun,
Weikun Ge,
Bo Shen,
Pengfei Tian,
Xinqiang Wang
A parallel-arrayed planar (PAP) strategy is proposed and applied for fabricating AlGaN-based deep-ultraviolet (DUV) micro-light-emitting diodes (μ-LEDs). The simultaneously demonstrated ultrahigh light output power, high wall-plug efficiency, and high modulation bandwidth shed light on the tremendous potential of the PAP strategy for fabricating DUV LEDs for multifunctional applications.
Abstract
Deep-ultraviolet (DUV) solar-blind communication (SBC) shows distinct advantages of non-line-of-sight propagation and background noise negligibility over conventional visible-light communication. AlGaN-based DUV micro-light-emitting diodes (µ-LEDs) are an excellent candidate for a DUV-SBC light source due to their small size, low power consumption, and high modulation bandwidth. A long-haul DUV-SBC system requires the light source exhibiting high output power, high modulation bandwidth, and high rate, simultaneously. Such a device is rarely reported. A parallel-arrayed planar (PAP) approach is here proposed to satisfy those requirements. By reducing the dimensions of the active emission mesa to micrometer scale, DUV µ-LEDs with ultrahigh power density are created due to their homogeneous injection current and enhanced planar isotropic light emission. Interconnected PAP µ-LEDs with a diameter of 25 µm are produced. This device has an output power of 83.5 mW with a density of 405 W cm−2 at 230 mA, a wall-plug efficiency (WPE) of 4.7% at 155 mA, and a high −3 dB modulation bandwidth of 380 MHz. The remarkable high output power and efficiency make those devices a reliable platform to develop high-modulation-bandwidth wireless communication and to meet the requirements for bio-elimination.
