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06 Dec 05:21

[ASAP] Tuning the Cross-Linker Crystallinity of a Stretchable Polymer Semiconductor

by Ging-Ji Nathan Wang, Yu Zheng, Song Zhang, Jiheong Kang, Hung-Chin Wu, Andrea Gasperini, Hongyi Zhang, Xiaodan Gu, Zhenan Bao

TOC Graphic

Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b04314
04 Dec 13:10

Carbazole–Dibenzofuran Dyads as Metal‐Free Single‐Component White‐Color Photoemitters

by Kenichi Tabata, Tetsuya Yamada, Hiroshi Kita, Yohei Yamamoto
Advanced Functional Materials Carbazole–Dibenzofuran Dyads as Metal‐Free Single‐Component White‐Color Photoemitters

White‐color light emitters from single organic molecule without heavy metals are prepared from newly synthesized carbazole–dibenzofuran dyads. Upon successive UV irradiation to the thin film of the dyad, dual phosphorescence bands appear at blue and yellow‐green regions. Furthermore, upon successive current flow, white‐color electroluminescence is attained.


Abstract

White‐color light emitters from single organic molecule without heavy metals are valuable for practical applications in organic light‐emitting devices. In this study, carbazole (Cz)–dibenzofuran (DBF) donor–acceptor dyads are designed for white‐color light emitters. Originally, these molecules show photoluminescence (PL) in near ultraviolet region. However, upon successive ultraviolet (UV) irradiation, white‐color PL appears, comprising dual‐color phosphorescence from the amorphous and crystalline state of the dyad. A continuous UV irradiation makes the twisting angle between the Cz and DBF planes flatten through the triplet‐excited state, which proceeds crystallization. Thermal annealing and UV irradiation can switch the blue‐ and white‐color phosphorescences from the dyad. Furthermore, charge injection generates white‐color electroluminescence. The materials with PL color modulation ability by UV‐light irradiation and heating can be applicable as light‐ and thermo‐sensors.

04 Dec 13:09

Multichannel Strategies to Produce Stabilized Azaphenalene Diradicals: A Predictable Model to Generate Self‐Doped Cathode Interfacial Layers for Organic Photovoltaics

by Xiaojun Yin, Xiaohui Liu, Yuhao Peng, Weixuan Zeng, Cheng Zhong, Guohua Xie, Lei Wang, Junfeng Fang, Chuluo Yang
Advanced Functional Materials Multichannel Strategies to Produce Stabilized Azaphenalene Diradicals: A Predictable Model to Generate Self‐Doped Cathode Interfacial Layers for Organic Photovoltaics

Multichannel strategies involving modulation of the counterions, end‐capped substituents, and dimerization are established to regulate the concentrations of azaphenalene diradicals for the first time. The generated anion‐radicals substantially decrease the work functions of the cathode. The all‐solution‐processed bulk heterojunction organic solar cells fabricated with azaphenalene salts based cathode interfacial layers achieve a high power conversion efficiency over 10%.


Abstract

Self‐doped cathode interfacial layers (CILs) are crucial to enable Ohmic‐like contact between the electrode and organic functional layers and thus profoundly promote the performances of organic optoelectronic devices. Herein, multifarious azaphenalene‐embedded organic salts with variable counterions, substituent groups, and repeating units are prepared, and their impacts on producing homologous diradicals are established. Electron paramagnetic resonance and X‐ray photoelectron spectroscopy studies reveal the existence of free radicals of these azaphenalene salts in the solid state. Density functional theory simulations indicate that the thermal energy of counterion‐induced proton transfer is crucial to produce diradicaloids, which can be manipulated in tailoring the azaphenalene backbones. Noticeably, the formed diradicaloids that are delocalized over the π‐conjugated systems will be beneficial to enhance the carrier density of the matrix and remarkably decrease the work functions of the Al electrode. The all‐solution‐processed bulk heterojunction organic solar cells are fabricated by employing them as CILs, which results in high power conversion efficiency of 10.24% in contrast to the 7.34% of the reference device without CILs.

04 Dec 13:09

Hydrogen‐Bonded Two‐Component Ionic Crystals Showing Enhanced Long‐Lived Room‐Temperature Phosphorescence via TADF‐Assisted Förster Resonance Energy Transfer

by Bo Zhou, Dongpeng Yan
Advanced Functional Materials Hydrogen‐Bonded Two‐Component Ionic Crystals Showing Enhanced Long‐Lived Room‐Temperature Phosphorescence via TADF‐Assisted Förster Resonance Energy Transfer

Two‐component co‐crystallized materials formed by melamine and isophthalic acid through hydrogen‐bonding exhibit ultralong room temperature phosphorescence (RTP) with lifetime for 2 seconds, which has been further designed for encryption and finger identification. Effective energy transfer occurs between melamine (thermally activated delayed fluorescence molecule) and isophtalic acid, like carriers in traps triggered by thermal excitation in inorganic persistent phosphors.


Abstract

Molecular room‐temperature phosphorescent (RTP) materials with long‐lived excited states have attracted widespread attention in the fields of optical imaging, displays, and sensors. However, accessing ultralong RTP systems remains challenging and examples are still limited to date. Herein, a thermally activated delayed fluorescence (TADF)‐assisted energy transfer route for the enhancement of persistent luminescence with an RTP lifetime as high as 2 s, which is higher than that of most state‐of‐the‐art RTP materials, is proposed. The energy transfer donor and acceptor species are based on the TADF and RTP molecules, which can be self‐assembled into two‐component ionic salts via hydrogen‐bonding interactions. Both theoretical and experimental studies illustrate the occurrence of effective Förster resonance energy transfer (FRET) between donor and acceptor molecules with an energy transfer efficiency as high as 76%. Moreover, the potential for application of the donor–acceptor cocrystallized materials toward information security and personal identification systems is demonstrated, benefitting from their varied afterglow lifetimes and easy recognition in the darkness. Therefore, the work described in this study not only provides a TADF‐assisted FRET strategy toward the construction of ultralong RTP, but also yields hydrogen‐bonding‐assembled two‐component molecular crystals for potential encryption and anti‐counterfeiting applications.

04 Dec 13:06

Electronic wavefunctions probed by all-optical attosecond interferometry

by Doron Azoury

Electronic wavefunctions probed by all-optical attosecond interferometry

Electronic wavefunctions probed by all-optical attosecond interferometry, Published online: 03 December 2018; doi:10.1038/s41566-018-0303-4

The absolute phase difference of the harmonic emission of Ar, Ne and He atoms is measured by XUV interferometry with temporal resolution of 6 as. This measurement provides a direct insight into the quantum properties of the photoelectron wavefunctions.
04 Dec 13:04

Large‐Area Organic Solar Cells: Material Requirements, Modular Designs, and Printing Methods

by Guodong Wang, Muhammad Abdullah Adil, Jianqi Zhang, Zhixiang Wei
Advanced Materials Large‐Area Organic Solar Cells: Material Requirements, Modular Designs, and Printing Methods

The rapid development in large‐area organic solar cells (OSCs) is reviewed. Materials requirements, modular designs, and printing methods for large‐area OSCs are discussed. By combining thick‐film material systems with efficient modular designs, and then by employing the right printing methods, the fabrication of large‐area OSCs will be successfully realized in the near future.


Abstract

The printing of large‐area organic solar cells (OSCs) has become a frontier for organic electronics and is also regarded as a critical step in their industrial applications. With the rapid progress in the field of OSCs, the highest power conversion efficiency (PCE) for small‐area devices is approaching 15%, whereas the PCE for large‐area devices has also surpassed 10% in a single cell with an area of ≈1 cm2. Here, the progress of this fast developing area is reviewed, mainly focusing on: 1) material requirements (materials that are able to form efficient thick active layer films for large‐area printing); 2) modular designs (effective designs that can suppress electrical, geometric, optical, and additional losses, leading to a reduction in the PCE of the devices, as a consequence of substrate area expansion); and 3) printing methods (various scalable fabrication techniques that are employed for large‐area fabrication, including knife coating, slot‐die coating, screen printing, inkjet printing, gravure printing, flexographic printing, pad printing, and brush coating). By combining thick‐film material systems with efficient modular designs exhibiting low‐efficiency losses and employing the right printing methods, the fabrication of large‐area OSCs will be successfully realized in the near future.

04 Dec 12:29

[ASAP] Tailored Phase Conversion under Conjugated Polymer Enables Thermally Stable Perovskite Solar Cells with Efficiency Exceeding 21%

by Lei Meng, Chenkai Sun, Rui Wang, Wenchao Huang, Zipeng Zhao, Pengyu Sun, Tianyi Huang, Jingjing Xue, Jin-Wook Lee, Chenhui Zhu, Yu Huang, Yongfang Li, Yang Yang

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/jacs.8b10520
29 Nov 13:45

A Cost Analysis of Fully Solution‐Processed ITO‐Free Organic Solar Modules

by Jie Guo, Jie Min
Advanced Energy Materials A Cost Analysis of Fully Solution‐Processed ITO‐Free Organic Solar Modules

Current cost drivers and potential avenues to reduce cost for organic solar modules by constructing a comprehensive bottom‐up cost model are examined. Moreover, the impact on the cost of alternative materials and constructions, process throughputs, module efficiency, and module lifetime, etc. is presented, and avenues for the further reduction of the minimum sustainable price and levelized cost of energy values are discussed.


Abstract

Organic photovoltaics (OPVs) have become a potential candidate for clean and renewable photovoltaic productions. This work examines the current cost drivers and potential avenues to reduce costs for organic solar modules by constructing a comprehensive bottom‐up cost model. The direct manufacturing cost (MC) and the minimum sustainable price (MSP) for an opaque single solar module (SSM) (MC = 187 ¥ m−2, MSP = 297 ¥ m−2) and for a tandem solar module (MC = 224 ¥ m−2, MSP = 438 ¥ m−2) are analyzed in detail. Within this calculation, the most expensive layers and processing steps are identified and highlighted. Importantly, the low levelized cost of energy (LCOE) value for an SSM with a 10% power conversion efficiency in a 20‐year range from 0.185 to 0.486 ¥ kWh−1, with a national average of 0.324 ¥ kWh−1 in China under an average solar irradiance of 1200 kWh m−2 year−1. Moreover, the impact on the cost of alternative materials and constructions, process throughputs, module efficiency, and module lifetime, etc., is presented and avenues to further reduce the MSP and LCOE values are indicated. The analysis shows that OPVs can emerge as a competitive alternative to established power generation technologies if the remaining issues (e.g., active layer material cost, module efficiency, and lifetime) can be resolved.

29 Nov 13:43

Theoretical efficiency limits of ideal coloured opaque photovoltaics

Energy Environ. Sci., 2019, Advance Article
DOI: 10.1039/C8EE03161D, Paper
Janne Halme, Pyry Mäkinen
Theoretical analysis connecting photovoltaics and colorimetry reveals the ultimate efficiency limits of colorful single-band-gap solar cells and modules.
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29 Nov 13:43

Boosting the ultra-stable unencapsulated perovskite solar cells by using montmorillonite/CH3NH3PbI3 nanocomposite as photoactive layer

Energy Environ. Sci., 2019, Advance Article
DOI: 10.1039/C8EE02958J, Paper
Hsin-Hsiang Huang, Yen-Chen Shih, Leeyih Wang, King-Fu Lin
The exMMTs, formed as a shell on top of CH3NH3PbI3 perovskite crystals, achieve ultra-stable unencapsulated PSCs.
To cite this article before page numbers are assigned, use the DOI form of citation above.
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28 Nov 11:14

A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

by Xunchang Wang, Zurong Du, Keke Dou, Huanxiang Jiang, Chenglin Gao, Liangliang Han, Renqiang Yang
Advanced Energy Materials A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

Four new polymers containing the novel asymmetrical backbone, thienobenzodithiophene, are synthesized and applied in high‐performance nonfullerene solar cells. The asymmetrical backbone can dramatically effect the polymer geometric configuration and modulate the polymer aggregation and crystallinity. This work reveals that the versatile asymmetric backbone is an excellent moiety to construct light‐harvesting copolymers and to modulate the microstructure for highly efficient PSCs.


Abstract

In this work, a new asymmetrical backbone thienobenzodithiophene (TBD) containing four aromatic rings is designed, and then four polymers PTBD‐BZ, PTBD‐BDD, PTBD‐FBT, and PTBD‐Tz are synthesized. The planar and high degree of π‐conjugation configuration can guarantee effective charge carrier transport and the distinct flanked dihedral angles between the TBD core and conjugated side chain can subtly regulate the molecular aggregation and crystallinity. The four polymer/3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone)‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]‐dithiophene (ITIC) blending films exhibit predominantly face‐on orientation. The photovoltaic devices based on wide bandgap polymers PTBD‐BZ and PTBD‐BDD achieve power conversion efficiencies (PCEs) as high as 12.02% and 11.39% without any post‐treatment. For the medium bandgap polymers PTBD‐FBT and PTBD‐Tz, the devices also show good PCEs of 10.18% and 11.02% with high V OC of 0.94 and 1.02 V, respectively, which indicates simultaneously achieving a V OC > 1 V and a high J SC is feasible to further improve the PSCs' performance by modifying this new backbone. This work reveals that the versatile asymmetric backbone is an excellent moiety to construct light‐harvesting copolymers and to modulate the microstructure for highly efficient PSCs.

27 Nov 23:33

Absence of Charge Transfer State Enables Very Low VOC Losses in SWCNT:Fullerene Solar Cells

by Andrej Classen, Lukas Einsiedler, Thomas Heumueller, Arko Graf, Maximilian Brohmann, Felix Berger, Simon Kahmann, Moses Richter, Gebhard J. Matt, Karen Forberich, Jana Zaumseil, Christoph J. Brabec
Advanced Energy Materials Absence of Charge Transfer State Enables Very Low VOC Losses in SWCNT:Fullerene Solar Cells

The absence of a charge transfer (CT) state is found in the (6,5) single‐walled carbon nanotube:PC70BM system and a detailed analysis of the open‐circuit voltage (V OC) is reported. The analysis reveals that the lack of the CT state enables very small radiative as well as nonradiative V OC losses for an organic cell, despite the ultranarrow bandgap of this system.


Abstract

Current state‐of‐the‐art organic solar cells (OSCs) still suffer from high losses of open‐circuit voltage (V OC). Conventional polymer:fullerene solar cells usually exhibit bandgap to V OC losses greater than 0.8 V. Here a detailed investigation of V OC is presented for solution‐processed OSCs based on (6,5) single‐walled carbon nanotube (SWCNT): [6,6]‐phenyl‐C71‐butyric acid methyl ester active layers. Considering the very small optical bandgap of only 1.22 eV of (6,5) SWCNTs, a high V OC of 0.59 V leading to a low E gap/qV OC = 0.63 V loss is observed. The low voltage losses are partly due to the lack of a measurable charge transfer state and partly due to the narrow absorption edge of SWCNTs. Consequently, V OC losses attributed to a broadening of the band edge are very small, resulting in V OC,SQV OC,rad = 0.12 V. Interestingly, this loss is mainly caused by minor amounts of SWCNTs with smaller bandgaps as well as (6,5) SWCNT trions, all of which are experimentally well resolved employing Fourier transform photocurrent spectroscopy. In addition, the low losses due to band edge broadening, a very low voltage loss are also found due to nonradiative recombination, ΔV OC,nonrad = 0.26 V, which is exceptional for fullerene‐based OSCs.

27 Nov 23:33

High‐Performance Large‐Area Organic Solar Cells Enabled by Sequential Bilayer Processing via Nonhalogenated Solvents

by Sheng Dong, Kai Zhang, Boming Xie, Jingyang Xiao, Hin‐Lap Yip, He Yan, Fei Huang, Yong Cao
Advanced Energy Materials High‐Performance Large‐Area Organic Solar Cells Enabled by Sequential Bilayer Processing via Nonhalogenated Solvents

A high‐performance (12.9%) non‐fullerene organic solar cell processed using a sequential bilayer deposition method from non‐halogenated solvents is reported. Using this method, the organic solar cell can be scaled up to a larger area (1 cm2) while maintaining a high performance of 11.4% by doctor‐blade coating. This method offers a truly compatible processing technique for printing large area organic solar cell modules.


Abstract

While the performance of laboratory‐scale organic solar cells (OSCs) continues to grow over 13%, the development of high‐efficiency large area OSCs still lags. One big challenge is that the formation of bulk heterojunction morphology is an extremely complicated process and the formed morphology is also a highly delicate balance involving many parameters such as domain size, purity, miscibility, etc. The morphology control becomes much more challenging when the device area is scaled up. In this work, a highly efficient (12.9%) nonfullerene organic solar cell processed using a sequential bilayer deposition method from nonhalogenated solvents, is reported. Using this bilayer processing method, the organic solar cells can be scaled up to a larger area (1 cm2) while maintaining a high performance of 11.4% using doctor‐blade‐coating technique. Moreover, as the acceptor is hidden behind the polymer donor, the possibility of degradation by sunlight is lessened. Thus, improved photostability is observed in the bilayer structure device when compared with the bulk heterojunction device. This method offers a truly compatible processing technique for printing large‐area OSC modules.

27 Nov 23:33

Metal Halide Perovskite Materials for Solar Cells with Long‐Term Stability

by Ziran Zhao, Feidan Gu, Haixia Rao, Senyun Ye, Zhiwei Liu, Zuqiang Bian, Chunhui Huang
Advanced Energy Materials Metal Halide Perovskite Materials for Solar Cells with Long‐Term Stability

The intrinsic instability of metal halide perovskites is one of the main factors that limit the commercialization of perovskite solar cells. This review highlights the recent progress in the composition engineering of metal halide perovskites for improving the stability of perovskite solar cells. The strategy of using mixed‐ion hybrid perovskites, low‐dimensional hybrid perovskites, and all‐inorganic perovskites is discussed in detail.


Abstract

Metal halide perovskite solar cells (PSCs) have emerged as promising candidates for photovoltaic technology with their power conversion efficiencies over 23%. For prototypical organic–inorganic metal halide perovskites, their intrinsic instability poses significant challenges to the commercialization of PSCs. Recently, the scientific community has done tremendous work in composition engineering to develop more robust light‐absorbing layers, including mixed‐ion hybrid perovskites, low‐dimensional hybrid perovskites, and all‐inorganic perovskites. This review provides an overview of the impact of these perovskites on the efficiency and long‐term stability of PSCs.

27 Nov 23:32

Synergistic Crystal and Interface Engineering for Efficient and Stable Perovskite Photovoltaics

by Mohammad Mahdi Tavakoli, Michael Saliba, Pankaj Yadav, Philippe Holzhey, Anders Hagfeldt, Shaik Mohammed Zakeeruddin, Michael Grätzel
Advanced Energy Materials Synergistic Crystal and Interface Engineering for Efficient and Stable Perovskite Photovoltaics

The bulk and surface defects of perovskite films are suppressed by using SnO2/TiO2 double layer oxide, addition of methylammonium chloride (MACl) as a crystallization aid to the precursor solution, and surface passivation of perovskite films with iodine solution, due to the formation of high‐quality large‐grain perovskite films and retardation of radiationless carrier recombination.


Abstract

The presence of bulk and surface defects in perovskite light harvesting materials limits the overall efficiency of perovskite solar cells (PSCs). The formation of such defects is suppressed by adding methylammonium chloride (MACl) as a crystallization aid to the precursor solution to realize high‐quality, large‐grain triple A‐cation perovskite films and that are combined with judicious engineering of the perovskite interface with the electron and hole selective contact materials. A planar SnO2/TiO2 double layer oxide is introduced to ascertain fast electron extraction and the surface of the perovskite facing the hole conductor is treated with iodine dissolved in isopropanol to passivate surface trap states resulting in a retardation of radiationless carrier recombination. A maximum solar to electric power conversion efficiency (PCE) of 21.65% and open circuit photovoltage (V oc) of ≈1.24 V with only ≈370 mV loss in potential with respect to the band gap are achieved, by applying these modifications. Additionally, the defect healing enhances the operational stability of the devices that retain 96%, 90%, and 85% of their initial PCE values after 500 h under continuously light illumination at 20, 50, and 65 °C, respectively, demonstrating one of the most stable planar PSCs reported so far.

27 Nov 23:32

Hole Transporting Monolayers: Self‐Assembled Hole Transporting Monolayer for Highly Efficient Perovskite Solar Cells (Adv. Energy Mater. 32/2018)

by Artiom Magomedov, Amran Al‐Ashouri, Ernestas Kasparavičius, Simona Strazdaite, Gediminas Niaura, Marko Jošt, Tadas Malinauskas, Steve Albrecht, Vytautas Getautis
Advanced Energy Materials Hole Transporting Monolayers: Self‐Assembled Hole Transporting Monolayer for Highly Efficient Perovskite Solar Cells (Adv. Energy Mater. 32/2018)

In article number 1801892, Steve Albrecht, Vytautas Getautis and co‐workers demonstrate a novel promising concept for the formation of a hole selective monolayer in perovskite solar cells. A low temperature dopant‐free technique makes it suitable for different substrates.


27 Nov 23:32

The Critical Impact of Material and Process Compatibility on the Active Layer Morphology and Performance of Organic Ternary Solar Cells

by Joo‐Hyun Kim, Charley Schaefer, Tingxuan Ma, Jingbo Zhao, Johnathan Turner, Masoud Ghasemi, Iordania Constantinou, Franky So, He Yan, Abay Gadisa, Harald Ade
Advanced Energy Materials The Critical Impact of Material and Process Compatibility on the Active Layer Morphology and Performance of Organic Ternary Solar Cells

Linear correlation of fill factor and relative standard deviation of fullerene distribution reveals that a ternary blend morphology with a uniform and pure mixed amorphous domain is required to achieve efficient ternary solar cells. This is achieved by the right kinetic path, controlled by the material and process compatibility.


Abstract

Although ternary solar cells (TSCs) offer a cost‐effective prospect to expand the absorption bandwidth of organic solar cells, only few TSCs have succeeded in surpassing the performance of binary solar cells (BSCs) primarily due to the complicated morphology of the ternary blends. Here, the key factors that create and limit the morphology and performance of the TSCs are elucidated. The origin of morphology formation is explored and the role of kinetic factors is investigated. The results reveal that the morphology of TSC blends considered in this study are characterized with either a single length‐scale or two length‐scale features depending on the composition of the photoactive polymers in the blend. This asymmetric morphology development reveals that TSC blend morphology critically depends on material compatibility and polymer solubility. Most interestingly, the fill factor (FF) of TSCs is found to linearly correlate with the relative standard deviation of the fullerene distribution at small lengths. This is the first time that such a correlation has been shown for ternary systems. The criteria that uniform sized and highly pure amorphous domains are accomplished through the correct kinetic path to obtain a high FF for TSCs are specifically elucidated. The findings provide a critical insight for the precise design and processing of TSCs.

27 Nov 23:31

Development of Next‐Generation Organic‐Based Solar Cells: Studies on Dye‐Sensitized and Perovskite Solar Cells

by Takurou N. Murakami, Nagatoshi Koumura
Advanced Energy Materials Development of Next‐Generation Organic‐Based Solar Cells: Studies on Dye‐Sensitized and Perovskite Solar Cells

Next‐generation solar cells consisting of organic materials are studied. To develop novel dyes for dye‐sensitized solar cells, the essential dye structures are explored to attain high efficiency. Additionally, the interfaces in the perovskite solar cells are characterized via electrochemical methods, and newly developed laser deposition methods for perovskite layers are discussed.


Abstract

Next‐generation organic solar cells such as dye‐sensitized solar cells (DSSCs) and perovskite solar cells (PSCs) are studied at the National Institute of Advanced Industrial Science and Technology (AIST), and their materials, electronic properties, and fabrication processes are investigated. To enhance the performance of DSSCs, the basic structure of an electron donor, π‐electron linker, and electron acceptor, i.e., D–π–A, is suggested. In addition, special organic dyes containing coumarin, carbazole, and triphenylamine electron donor groups are synthesized to find an effective dye structure that avoids charge recombination at electrode surfaces. Meanwhile, PSCs are manufactured using both a coating method and a laser deposition technique. The results of interfacial studies demonstrate that the level of the conduction band edge (CBE) of a compact TiO2 layer is shifted after TiCl4 treatment, which strongly affects the solar cell performance. Furthermore, a special laser deposition system is developed for the fabrication of the perovskite layers of PSCs, which facilitates the control over the deposition rate of methyl ammonium iodide used as their precursor.

27 Nov 23:23

[ASAP] From Fundamental Theories to Quantum Coherences in Electron Transfer

by Shahnawaz Rafiq, Gregory D. Scholes

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/jacs.8b09059
19 Nov 04:55

[ASAP] Effects of Molecular Orientation of a Fullerene Derivative at the Donor/Acceptor Interface on the Device Performance of Organic Photovoltaics

by Kouki Akaike, Takumi Kumai, Kyohei Nakano, Shed Abdullah, Shun Ouchi, Yuuki Uemura, Yuta Ito, Akira Onishi, Hiroyuki Yoshida, Keisuke Tajima, Kaname Kanai

TOC Graphic

Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b03659
19 Nov 04:55

[ASAP] Conjugated Polymers Based on Thiazole Flanked Naphthalene Diimide for Unipolar n-Type Organic Field-Effect Transistors

by Long Zhang, Zhongli Wang, Chunhui Duan, Zhenfeng Wang, Yunfeng Deng, Jiantie Xu, Fei Huang, Yong Cao

TOC Graphic

Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b03902
19 Nov 04:54

[ASAP] Dual-Accepting-Unit Design of Donor Material for All-Small-Molecule Organic Solar Cells with Efficiency Approaching 11%

by Yong Huo, Xiao-Ting Gong, Tsz-Ki Lau, Tong Xiao, Cenqi Yan, Xinhui Lu, Guanghao Lu, Xiaowei Zhan, Hao-Li Zhang

TOC Graphic

Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b03980
19 Nov 01:33

[ASAP] Unveiling the Role of tBP–LiTFSI Complexes in Perovskite Solar Cells

by Shen Wang, Zihan Huang, Xuefeng Wang, Yingmin Li, Marcella Günther, Sophia Valenzuela, Pritesh Parikh, Amanda Cabreros, Wei Xiong, Ying Shirley Meng

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/jacs.8b09809
15 Nov 01:50

Ternary non-fullerene polymer solar cells with a high crystallinity n-type organic semiconductor as the second acceptor

J. Mater. Chem. A, 2018, 6,24814-24822
DOI: 10.1039/C8TA08406H, Paper
Lian Zhong, Haijun Bin, Yongxi Li, Ming Zhang, Jianqiu Xu, Xiaojun Li, He Huang, Qin Hu, Zuo-Quan Jiang, Jing Wang, Chunfeng Zhang, Feng Liu, Thomas P. Russell, Zhanjun Zhang, Yongfang Li
Ternary blend is an effective way to realize high photovoltaic performance of polymer solar cells (PSCs). A highly crystalline n-type organic semiconductor (n-OS) IDIC was introduced into a low crystalline blend of conjugated polymer donor J61 and n-OS acceptor BT-IC.
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14 Nov 17:00

A Self‐Organized Poly(vinylpyrrolidone)‐Based Cathode Interlayer in Inverted Fullerene‐Free Organic Solar Cells

by Bei Yang, Shaoqing Zhang, Sunsun Li, Huifeng Yao, Wanning Li, Jianhui Hou
Advanced Materials A Self‐Organized Poly(vinylpyrrolidone)‐Based Cathode Interlayer in Inverted Fullerene‐Free Organic Solar Cells

The utilization of poly(vinylpyrrolidone) (PVP) as a cathode interlayer is demonstrated in inverted and conventional devices via both the self‐organization method and the step‐by‐step preparation method. The driving forces for PVP migration are the high surface energy of the PVP and the strong intermolecular interaction between the PVP and the bottom cathode. In addition, the PVP‐modified devices have excellent stability in air and show insensitivity to PVP molecular weight.


Abstract

Herein, poly(vinylpyrrolidone) (PVP) is used as the cathode interlayer (CIL) through the self‐organization method in inverted organic solar cells (OSCs). By coating a solution of PVP and active layer materials onto a glass/indium tin oxide (ITO) substrate, the PVP can segregate to the near ITO side due to its high surface energy and strong intermolecular interaction with the ITO electrode. The power conversion efficiency (PCE) of the obtained OSC device reaches 13.3%, much higher than that of the control device with a PCE of only 10.1%. The improvement results from the increased exciton dissociation efficiency and the depressed trap‐assisted recombination, which can be attributed to the reduced work function of the cathode by the self‐organized PVP. Additionally, the molecular weight of the PVP has almost no influence on the device performance, and the PVP‐modified device presents superior stability. This method can also be applied in other highly efficient fullerene‐free OSCs, and with a fine selection of the active layer, a high PCE of 14.0% is obtained. Overall, this work demonstrates the great potential of the PVP‐based CIL in inverted OSCs fabricated via the self‐organization method.

14 Nov 15:55

[ASAP] Interfacial TADF Exciplex as a Tool to Localize Excitons, Improve Efficiency, and Increase OLED Lifetime

by Marco Colella, Piotr Pander, Daniel de Sa Pereira, Andrew P. Monkman

TOC Graphic

ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.8b15942
13 Nov 17:32

Materials toward the Upscaling of Perovskite Solar Cells: Progress, Challenges, and Strategies

by Fangfang Wang, Yezhou Cao, Cheng Chen, Qing Chen, Xiao Wu, Xinguo Li, Tianshi Qin, Wei Huang
Advanced Functional Materials Materials toward the Upscaling of Perovskite Solar Cells: Progress, Challenges, and Strategies

Perovskite solar cells (PSCs) have undergone rapid development, but the performance degradation accompanied by device upscaling urgently needs a solution. This review covers the research progress on each functional material of large‐area PSCs. A conclusion on the main challenges and an outlook on the research direction of large‐area PSCs are provided.


Abstract

Perovskite solar cells (PSCs) are promising candidates for the next generation of photovoltaic technologies due to their constantly improved efficiencies, which gain much attention from both the scientific and industrial communities. Although the performance of PSCs is dramatically enhanced, most certified or reported high‐efficiency PSCs are still limited to a relatively small active area. The degradation of efficiency and stability accompanied by upscaling must be solved, being a bottleneck toward industrialization. This review focuses on the research progress, challenges, and strategies on large‐area PSCs, especially each functional material in various device architectures, including perovskites, hole transport materials, electron transport materials, and electrodes. Finally, the main issues related to each functional layer of PSCs from laboratory to industry are presented and an outlook on the research direction of large‐area PSCs is given.

13 Nov 17:27

Effect of Triplet Confinement on Triplet–Triplet Annihilation in Organic Phosphorescent Host–Guest Systems

by Arnout Ligthart, Xander de Vries, Le Zhang, Mike C. W. M. Pols, Peter A. Bobbert, Harm van Eersel, Reinder Coehoorn
Advanced Functional Materials Effect of Triplet Confinement on Triplet–Triplet Annihilation in Organic Phosphorescent Host–Guest Systems

The efficiency of phosphorescent organic light emitting diodes (OLEDs) decreases with increasing luminance (“roll‐off”). One of the contributions to the roll‐off is triplet–triplet annihilation (TTA). The TTA‐loss for 22 host–guest systems is measured, and the role of the direct TTA process and of triplet diffusion is disentangled and quantified using a recently proposed analysis method and kinetic Monte Carlo simulations.


Abstract

The efficiency of phosphorescent organic light emitting diodes (OLEDs) shows a decrease with increasing luminance (“roll‐off”). One of the contributions to the roll‐off is triplet–triplet annihilation (TTA). TTA is the process of energy transfer from one triplet exciton to another, after which the excited exciton decays nonradiatively to the lowest triplet state. In this study, the TTA‐rate is measured for a large number of emissive materials consisting of a small concentration of phosphorescent “guest” molecules, with emission colors across the entire visible range, embedded in various host materials. It is found that the TTA‐rate does not only depend on the direct interaction rate between the excitons on the guest molecules, but also on the difference in triplet energy ΔE T of the host and guest molecules: when ΔE T is smaller than about 0.20 eV, diffusion of excitons via the host molecules leads to a significant enhancement of the TTA‐rate. By varying the guest concentration and using kinetic Monte Carlo simulations, the roles of the direct interaction, guest‐mediated diffusion, and host‐mediated diffusion are disentangled.

13 Nov 17:11

Fast Deposition of Aligning Edge‐On Polymers for High‐Mobility Ambipolar Transistors

by Yingying Jiang, Jinyang Chen, Yunlong Sun, Qingyuan Li, Zhengxu Cai, Junyu Li, Yunlong Guo, Wenping Hu, Yunqi Liu
Advanced Materials Fast Deposition of Aligning Edge‐On Polymers for High‐Mobility Ambipolar Transistors

Large‐area few‐layer polymer films are prepared using bar‐coating methods at a speed of 120 mm s−1. The morphology and crystalline analysis indicates that the polymer grains are uniformly oriented and the polymer backbones are in the same direction. The resulting mobility is up to 5.5/4.5 cm2 V−1 s−1, which is nine times higher than spin‐coating case.


Abstract

Fast deposition of aligning ambipolar polymers for high‐performance organic field‐effect transistors (OFETs) and inverter circuits are highly desired for both scientific studies and industry applications. Here, large‐area and ordered polymer films are prepared by a bar‐coating method at a rate of 120 mm s−1 in air. Atomic force microscopy and grazing‐incidence wide‐angle X‐ray scattering analysis indicate uniform edge‐on poly(fluoroisoindigo‐difluorobithiophene‐fluoroisoindigo‐bithiophene) (PFIBI‐BT) in 11.7 ± 1 nm film (≈5 layers). The elongated, uniformly oriented grains can reduce the adverse effects of the grain boundaries and facilitate charge transport in polymers. Furthermore, OFETs based on parallel film show high hole/electron mobilities up to 5.5/4.5 cm2 V−1 s−1, which are approximately nine times of the devices prepared by spin‐coating. The gain of the inverter is as high as 174, which is one of the highest values in polymer inventers currently. These results demonstrate that the excellent bipolar performance of few‐layer PFIBI‐BT can be ensured while achieving the compatibility of the experimental process with industrial preparation.

12 Nov 00:12

[ASAP] De Novo Design of Phototheranostic Sensitizers Based on Structure-Inherent Targeting for Enhanced Cancer Ablation

by Mingle Li, Saran Long, Yao Kang, Lianying Guo, Jingyun Wang, Jiangli Fan, Jianjun Du, Xiaojun Peng

TOC Graphic

Journal of the American Chemical Society
DOI: 10.1021/jacs.8b09117