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Thi Huong Le, Quang-Duy Dao, Mai-Phuong Nghiêm, Sébastien Péralta, Regis Guillot, Quoc Nghi Pham, Akihiko Fujii, Masanori Ozaki, Fabrice Goubard, Thanh-Tuân Bui
Two readily accessible thienothiophene-triphenylamine charge-transport materials have been synthesized by simply varying the substitution pattern of the triphenylamine groups on a central thienothiophene π-linker. The impact of the substitution pattern on the thermal, photoelectrochemical, and photovoltaic properties of these materials was evaluated and, based on theoretical and experimental studies, we found that the isomer in which the triphenylamine groups were located at the 2,5-positions of the thienothiophene core (TT-2,5-TPA) had better π-conjugation than the 3,6-isomer (TT-3,6-TPA)...
April 25, 2018: Chemistry, An Asian Journal
Ashok Zachariah Samuel, Hiro-O Hamaguchi
A general method for estimating lamella thickness distribution in semi-crystalline polymers has been developed and applied to polyethylene (PE). The Longitudinal acoustic mode (LAM) of PE appears at very low frequencies (8 to 20 cm-1) in the Raman spectrum. It represents a distribution of lamellae of varying thicknesses. We propose here a distribution function that converts a low frequency LAM Raman band to the corresponding lamellae thicknesses distribution. Using this distribution function, we study lamella formation in crystallizing PE to elucidate the influence of supercooling, critical lamella thickness, minimum chain length at which folding occurs and determine associated thermodynamic parameters accurately...
April 24, 2018: Chemistry: a European Journal
Wu-Qiang Wu, Qi Wang, Yanjun Fang, Yuchuan Shao, Shi Tang, Yehao Deng, Haidong Lu, Ye Liu, Tao Li, Zhibin Yang, Alexei Gruverman, Jinsong Huang
The efficiencies of perovskite solar cells (PSCs) are now reaching such consistently high levels that scalable manufacturing at low cost is becoming critical. However, this remains challenging due to the expensive hole-transporting materials usually employed, and difficulties associated with the scalable deposition of other functional layers. By simplifying the device architecture, hole-transport-layer-free PSCs with improved photovoltaic performance are fabricated via a scalable doctor-blading process. Molecular doping of halide perovskite films improved the conductivity of the films and their electronic contact with the conductive substrate, resulting in a reduced series resistance...
April 24, 2018: Nature Communications
Shaykha Alzahly, LePing Yu, Cameron J Shearer, Christopher T Gibson, Joseph G Shapter
Molybdenum disulphide (MoS₂) is one of the most studied and widely applied nanomaterials from the layered transition-metal dichalcogenides (TMDs) semiconductor family. MoS₂ has a large carrier diffusion length and a high carrier mobility. Combining a layered structure of single-wall carbon nanotube (SWCNT) and MoS₂ with n-type silicon (n-Si) provided novel SWCNT/n-Si photovoltaic devices. The solar cell has a layered structure with Si covered first by a thin layer of MoS₂ flakes and then a SWCNT film...
April 21, 2018: Materials
Yumin Zhang, Jianhong Zhao, Jin Zhang, Xixi Jiang, Zhongqi Zhu, Qingju Liu
A printing process for the fabrication of perovskite solar cells (PSCs) exhibits promising future application in the photovoltaic industry due to its low-cost and eco-friendly preparation. In mesoscopic carbon-based PSCs, however, compared to conventional ones, the hole-transport-layer-free PSCs often lead to inefficient hole extraction. Here, we used liquid metal (LM, Galinstan) as an interface modifier material in combination with a carbon electrode. Considering the high conductivity and room-temperature fluidity, it is found that LMs are superior in improving hole extraction and, more importantly, LMs tend to be reserved at the interface between ZrO2 and carbon for enhancing the contact property...
April 24, 2018: ACS Applied Materials & Interfaces
Jonas Alexander Schwenzer, Lucija Rakocevic, Robert Gehlhaar, Tobias Abzieher, Saba Gharibzadeh, Somayeh Moghadamzadeh, Aina Quintilla, Bryce Sydney Richards, Uli Lemmer, Ulrich Wilhelm Paetzold
This paper reports on the impact of outdoor temperature variations on the performance of methylammonium lead iodide (MAPI) perovskite solar cells (PSCs). It shows that, as expected from the theory for a conventional solar cell, the open-circuit voltage (VOC) of a PSC decreases with increasing temperature. However, in contrast to these expected trends, the current density (JSC) of PSCs is found to decline strongly below 20% of the initial value upon cycling the temperatures from 10 °C to 60 °C and back. This decline in current density is driven by an increasing series resistance and caused by the fast temperature variations as it is not apparent for solar cells exposed to constant temperatures of the same range...
April 24, 2018: ACS Applied Materials & Interfaces
Anil Kanwat, Eric Moyen, Sinyoung Cho, Jin Jang
Incorporation of Rubidium (Rb) into mixed lead halide perovskites has recently achieved record power conversion efficiency and excellent stability in perovskite solar cells. Inspired by these tremendous advances in photovoltaics, this study demonstrates the impact of Rb incorporation into MAPbBr3-based light emitters. Rb partially substitutes MA (methyl ammonium), resulting in a mixed cation perovskite with the formula MA(1-x)RbxPbBr3. Pure MAPbBr3 crystallizes into a polycrystalline layer with highly defective sub-micrometer grains...
April 24, 2018: ACS Applied Materials & Interfaces
Ze-Kun Yang, Ning-Xin Xu, Ryo Takita, Atsuya Muranaka, Chao Wang, Masanobu Uchiyama
π-Conjugated polymers are widely used in optoelectronics for fabrication of organic photovoltaic devices, organic light-emitting diodes, organic field effect transistors, and so on. Here we describe the protocol for polycondensation of bifunctional aryl ethers or aryl ammonium salts with aromatic dimetallic compounds through cleavage of inert C-O/C-N bonds. This reaction proceeds smoothly in the presence of commercially available Ni/Pd catalyst under mild conditions, affording the corresponding π-conjugated polymers with high molecular weight...
April 23, 2018: Nature Communications
Yicheng Zhao, Hairen Tan, Haifeng Yuan, Zhenyu Yang, James Z Fan, Junghwan Kim, Oleksandr Voznyy, Xiwen Gong, Li Na Quan, Chih Shan Tan, Johan Hofkens, Dapeng Yu, Qing Zhao, Edward H Sargent
Formamidinium-lead-iodide (FAPbI3 )-based perovskites with bandgap below 1.55 eV are of interest for photovoltaics in view of their close-to-ideal bandgap. Record-performance FAPbI3 -based solar cells have relied on fabrication via the sequential-deposition method; however, these devices exhibit unstable output under illumination due to the difficulty of incorporating cesium cations (stabilizer) in sequentially deposited films. Here we devise a perovskite seeding method that efficiently incorporates cesium and beneficially modulates perovskite crystallization...
April 23, 2018: Nature Communications
Jixian Xu, Oleksandr Voznyy, Mengxia Liu, Ahmad R Kirmani, Grant Walters, Rahim Munir, Maged Abdelsamie, Andrew H Proppe, Amrita Sarkar, F Pelayo García de Arquer, Mingyang Wei, Bin Sun, Min Liu, Olivier Ouellette, Rafael Quintero-Bermudez, Jie Li, James Fan, Lina Quan, Petar Todorovic, Hairen Tan, Sjoerd Hoogland, Shana O Kelley, Morgan Stefik, Aram Amassian, Edward H Sargent
Colloidal quantum dots (CQDs) are promising photovoltaic (PV) materials because of their widely tunable absorption spectrum controlled by nanocrystal size1,2 . Their bandgap tunability allows not only the optimization of single-junction cells, but also the fabrication of multijunction cells that complement perovskites and silicon 3 . Advances in surface passivation2,4-7 , combined with advances in device structures 8 , have contributed to certified power conversion efficiencies (PCEs) that rose to 11% in 2016 9 ...
April 23, 2018: Nature Nanotechnology
Henry J Snaith
No abstract text is available yet for this article.
May 2018: Nature Materials
Kan Ding, Xiao Liu, Stephen R Forrest
Experimental and theoretical approaches are used to understand the role of nanomorphology on exciton dissociation and charge collection at dilute donor-acceptor (D-A) organic heterojunctions. Specifically, two charge transfer (CT) states in D-A mixed HJs comprising nanocrystalline domains of tetraphenyldibenzoperiflanthene (DBP) as the donor and C70 as the acceptor are unambiguously related to the nanomorphology of the mixed layer. Alternating DBP:C70 multilayer stacks are used to identify and control the optical properties of the CT states, as well as to simulate the dilute mixed heterojunctions...
April 23, 2018: Nano Letters
Max A Mattson, Thomas D Green, Peter T Lake, Martin McCullagh, Amber T Krummel
Perylene diimides (PDI) are a family of molecules that have potential applications to organic photovoltaics. These systems typically aggregate cofacially due to π-stacking interactions between the aromatic perylene cores. In this study, the structure and characteristics of aggregated N,N'-bis(2,6-diisopropylphenyl)-3,4,9,10-perylenetetracarboxylic diimide (common name lumogen orange), a perylene diimide (PDI) with sterically bulky imide functional groups were investigated using both experimental vibrational spectroscopy and molecular dynamics (MD) simulations...
April 23, 2018: Journal of Physical Chemistry. B
Anders S Gertsen, Mads Koerstz, Kurt V Mikkelsen
Photon upconversion facilitated by triplet-triplet annihilation in molecular systems is a promising path toward utilization of sub bandgap photons in photovoltaic devices. Prior to the challenging synthesis of new molecules, quantum chemical computations can aid the design process and provide suggestions for new and optimal systems. Here, we benchmark time-dependent density functional methods by their ability to describe relevant photophysical quantities of a range of different types of sensitizer/annihilator pairs to provide guidelines for future computational studies of potential new pairs...
April 23, 2018: Physical Chemistry Chemical Physics: PCCP
Geert Pirotte, Jurgen Kesters, Tom Cardeynaels, Pieter Verstappen, Jan D'Haen, Laurence Lutsen, Benoît Champagne, Dirk Vanderzande, Wouter Maes
Push-pull-type conjugated polymers applied in organic electronics do not always contain a perfect alternation of donor and acceptor building blocks. Misscouplings can occur, which have a noticeable effect on the device performance. In this work, the influence of homocoupling on the optoelectronic properties and photovoltaic performance of PDTSQxff polymers is investigated, with a specific focus on the quinoxaline acceptor moieties. A homocoupled biquinoxaline segment is intentionally inserted in specific ratios during the polymerization...
April 22, 2018: Macromolecular Rapid Communications
Chenxin Ran, Jiantie Xu, Weiyin Gao, Chunmao Huang, Shixue Dou
The rapid development of solar cells (SCs) based on organic-inorganic hybrid metal triiodide perovskite (MTP) materials holds great promise for next-generation photovoltaic devices. The demonstrated power conversion efficiency of the SCs based on MTP (PSCs for short) has reached over 20%. An MTP material is a kind of soft ionic solid semiconductor. The intrinsic optoelectronic properties of MTP are greatly determined by several factors, such as the crystalline phase, doping type, impurities, elemental composition, and defects in its crystal structure...
April 23, 2018: Chemical Society Reviews
Akshay A Murthy, Teodor K Stanev, Jeffrey D Cain, Shiqiang Hao, Trevor LaMountain, Sung Kyu Kim, Nathaniel A Speiser, Kenji Watanabe, Takashi Taniguchi, Chris Wolverton, Nathaniel P Stern, Vinayak P Dravid
Understanding the electronic transport of monolayer transition metal dichalcogenides (TMDs) and their heterostructures is complicated by the difficulty in achieving electrical contacts that do not perturb the material. Typically, metal deposition on monolayer TMDs leads to hybridization between the TMD and the metal, which produces Schottky barriers at the metal semiconductor interface. In this work, we apply the recently reported hexagonal boron nitride (h-BN) tunnel contact scheme to probe the junction characteristics of a lateral TMD heterostructure grown via chemical vapor deposition...
April 20, 2018: Nano Letters
Liqiang Huang, Gang Wang, Weihua Zhou, Boyi Fu, Xiaofang Cheng, Lifu Zhang, Zhibo Yuan, Sixing Xiong, Lin Zhang, Yuanpeng Xie, Andong Zhang, Youdi Zhang, Wei Ma, Weiwei Li, Yinhua Zhou, Elsa Reichmanis, Yiwang Chen
High efficiency organic solar cells (OSCs) can be produced through optimization of component molecular design, coupled with interfacial engineering and control of active layer morphology. However, vertical stratification of the bulk-heterojunction (BHJ), a spontaneous activity which occurs during the drying process, remains an intricate problem yet to be solved. Routes toward regulating the vertical separation profile and evaluating the effects on the final device should be explored to further enhance the performance of OSCs...
April 20, 2018: ACS Nano
Geon Hyeong Lee, Young Sik Kim
A novel quinoxaline-based organic dye with heteroleptic dual electron donors (phenoxazine and carbazole) on each side of a quinoxaline was designed, and its electronic and optical properties were investigated theoretically for applications to dye-sensitized solar cells (DSSCs). To understand the factors influencing the photovoltaic efficiency, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations of these dyes were performed. The absorption spectrum of the dyes showed different forms because of the different energy levels of the molecular orbital (MO) of each dye and the intramolecular charge-transfer (ICT) characteristics...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Geon Hyeong Lee, Young Sik Kim
In this study, phenoxazine (PXZ)-based dye sensitizers with triphenylamine (TPA) as a dual-electron donor and thiophen and benzothiadiazole (BTD) or 4,7-diethynylbenzo[c][1,2,5]thiadiazole (DEBT) as an electron acceptor (dye1, dye2, and dye3) were designed and investigated. dye3 can significantly stabilize the lowest unoccupied molecular orbital (LUMO) energy level of an organic dye. We used density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to better understand the factors responsible for the photovoltaic performance...
September 1, 2018: Journal of Nanoscience and Nanotechnology
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