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Xiaoqing Jiang, Ze Yu, Yuchen Zhang, Jianbo Lai, Jiajia Li, Gagik G Gurzadyan, Xichuan Yang, Licheng Sun
Herein, we successfully applied a facile in-situ solid-state synthesis of conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as a HTM, directly on top of the perovskite layer, in conventional mesoscopic perovskite solar cells (PSCs) (n-i-p structure). The fabrication of the PEDOT film only involved a very simple in-situ solid-state polymerisation step from a monomer 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) made from a commercially available and cheap starting material. The ultraviolet photoelectron spectroscopy (UPS) demonstrated that the as-prepared PEDOT film possesses the highest occupied molecular orbital (HOMO) energy level of -5...
February 13, 2017: Scientific Reports
D M Juraschek, M Fechner, N A Spaldin
We describe a mechanism by which nonlinear phononics allows ultrafast coherent and directional control of transient structural distortions. With ErFeO_{3} as a model system, we use density functional theory to calculate the structural properties as input into an anharmonic phonon model that describes the response of the system to a pulsed optical excitation. We find that the trilinear coupling of two orthogonal infrared-active phonons to a Raman-active phonon causes a transient distortion of the lattice. In contrast to the quadratic-linear coupling that has been previously explored, the direction of the distortion is determined by the polarization of the exciting light, introducing a novel mechanism for nonlinear phononic switching...
February 3, 2017: Physical Review Letters
Li-Qiang Xie, Liang Chen, Zi-Ang Nan, Hai-Xin Lin, Tan Wang, Dongping Zhan, Jia-Wei Yan, Bing-Wei Mao, Zhong-Qun Tian
The spontaneous α-to-δ phase transition of the Formamidinium-based (FA) lead halide perovskite hinders its large scale application in solar cells. Though this phase transition can be inhibited by alloying with Methylammonium-based (MA) perovskite, the underlying mechanism is largely unexplored. In this communication, we grow high quality mixed cations and halides perovskite single crystals (FAPbI3)1-x(MAPbBr3)x to understand the principles for maintaining pure perovskite phase, which is essential to device optimization...
February 17, 2017: Journal of the American Chemical Society
Runjiang Guo, Yiping Guo, Huanan Duan, Hua Li, Hezhou Liu
In recent years, the lead-free piezoelectric nanogenerators have attracted much attention, because of their great potential for harvesting energy from our environment. Here, we report on the first synthesis of two-dimensional (2D) single crystal ZnSnO3 hexagon nanoplates and fabrication of nanogenerators based on the single crystal ZnSnO3 nanoplates. The orthorhombic perovskite structured ZnSnO3 nanoplates with the (111) facets exposed at the surface of the plates are successfully synthesized via a one-step hydrothermal reaction...
February 17, 2017: ACS Applied Materials & Interfaces
Haejun Yu, Jaehoon Ryu, Jong Woo Lee, Jongmin Roh, Kisu Lee, Juyoung Yun, Jungsup Lee, Yun Ki Kim, Doyk Hwang, Jooyoun Kang, Seong Keun Kim, Jyongsik Jang
There remains tremendous interest in perovskite solar cells (PSCs) in the solar energy field; the certified power conversion efficiency (PCE) now exceeds 20 %. Along with research focused on enhancing PCE, studies are also underway concerning PSC commercialization. It is crucial to simplify the fabrication process and reduce the production cost to facilitate commercialization. Herein, we successfully fabricated highly efficient hole-blocking layer (HBL)-free PSCs through vigorously interrupting penetration of hole-transport material (HTM) into FTO by large grain based-CH3NH3PbI3 (MAPbI3) film, thereby obtaining a PCE of 18...
February 17, 2017: ACS Applied Materials & Interfaces
Songtao Chen, Cheng Zhang, Joonhee Lee, Jung Han, Arto Nurmikko
A vertical-cavity surface-emitting perovskite laser is achieved using a microcavity configuration where CH3 NH3 PbI3 thin solid films are embedded within a custom GaN-based high-quality (Q-factor) resonator. This single-mode perovskite laser reaches a low threshold (≈7.6 µJ cm(-2) ) at room temperature and emits spatially coherent Gaussian laser beams. The devices allow direct access to the study of perovskite gain dynamics and material robustness.
February 17, 2017: Advanced Materials
Phil Szuromi
No abstract text is available yet for this article.
February 17, 2017: Science
Dongsheng Chen, Yanyan Zhu
CH3NH3PbI3 perovskite nanofibers were synthesized by versatile electrospinning techniques. The synthetic CH3NH3PbI3 nanofibers were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and photoluminescence. As counter electrodes, the synthesized nanofibers increased the performance of the dye-sensitized solar cells from 1.58 to 2.09%. This improvement was attributed to the enhanced smoothness and efficiency of the electron transport path. Thus, CH3NH3PbI3 perovskites nanofibers are potential alternative to platinum counter electrodes in dye-sensitized solar cells...
December 2017: Nanoscale Research Letters
Kelsey A Stoerzinger, Ryan B Comes, Steven R Spurgeon, Suntharampillai Thevuthasan, Kyuwook Ihm, Ethan J Crumlin, Scott A Chambers
The polarity of oxide surfaces can dramatically impact their surface reactivity, in particular with polar molecules such as water. The surface species that result from this interaction change the oxide electronic structure and chemical reactivity in applications such as photoelectrochemistry, but are challenging to probe experimentally. Here we report a detailed study of the surface chemistry and electronic structure of the perovskite LaFeO3 in humid conditions using ambient pressure X-ray photoelectron spectroscopy...
February 16, 2017: Journal of Physical Chemistry Letters
Jiangang Feng, Xiaoxu Yan, Yun Liu, Hanfei Gao, Yuchen Wu, Bin Su, Lei Jiang
Polarization-sensitive perovskite photodetectors are realized by crystallographically aligning 1D perovskite arrays. High-quality inorganic perovskite single crystals with crystallographic order are fabricated by strictly manipulating the dewetting process of organic solution, yielding photodetectors with high photoresponsivity and fast response speed.
February 15, 2017: Advanced Materials
Ze Yu, Xiaoqing Jiang, Jianbo Lai, Yuchen Zhang, Maowei Hu, Ning Lei, Dongping Wang, Xichuan Yang, Licheng Sun
In high-performance perovskite solar cells (PSCs), hole-transporting materials (HTMs) play important roles in extracting and transporting the photo-generated holes from the perovskite absrorber to the cathode, thus reducing unwanted recombination losses and enhancing the photovoltaic performance. Herein, solution-processable tetra-4-(bis(4-tert-butyl)phenyl)amino)phenoxy-substituted copper phthalocyanine (CuPc-OTPAtBu) has been synthesized and explored as a HTM in PSCs. The optical, electrochemical and thermal properties are fully characterized for this organic metal complex...
February 15, 2017: ChemSusChem
Paula Kayser, Sean Injac, Brendan J Kennedy, Andre L Menezes de Oliveira, Yuichi Shirako, Masashi Hasegawa
The temperature dependences of the structures of three polytypes of BaRuO3 have been investigated between room temperature and 1000 °C using high resolution synchrotron X-ray diffraction. The structural studies reveal a systematic decrease of the Ru-Ru distance as the pressure required to prepare the polytype increases. The O-O distance across the shared face increases as the Ru-Ru separation decreases. The 9R and 4H polytypes undergo unexceptional changes with increasing temperature. In 6H-BaRuO3 there is an apparent increase in the Ru-Ru interaction at around 650 °C and a concurrent reduction in the O-O distance, indicating an anomalous strengthening of the Ru-Ru interactions upon heating...
February 15, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Aditya Sharma, Mayora Varshney, Weon Cheol Lim, Hyun-Joon Shin, Jitendra Pal Singh, Sung Ok Won, Keun Hwa Chae
Correlations among the B-O6 octahedra distortions, existing polymorphous phases, band structures and electronic conductivities of ABO3 perovskites are matters for debate and require a deep understanding of their local atomic/electronic structures and diverse assets. In this study, to illustrate the distortion in V-O6 octahedra and its implication on the band structure and electronic properties, spectroscopic investigations on the RF-sputtering grown insulating SrVO3 thin films were employed using X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)...
February 15, 2017: Physical Chemistry Chemical Physics: PCCP
Gengwu Ji, Guanhaojie Zheng, Bin Zhao, Fei Song, Xiaonan Zhang, Kongchao Shen, Yingguo Yang, Yimin Xiong, Xingyu Gao, Liang Cao, Dong-Chen Qi
The electronic structures of rubrene films deposited on CH3NH3PbI3 perovskite have been investigated using in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). It was found that rubrene molecules interacted weakly with the perovskite substrate. Due to charge redistribution at their interface, a downward 'band bending'-like energy shift of ∼0.3 eV and an upward band bending of ∼0.1 eV were identified at the upper rubrene side and the CH3NH3PbI3 substrate side, respectively...
February 15, 2017: Physical Chemistry Chemical Physics: PCCP
Yuto Miyahara, Kohei Miyazaki, Tomokazu Fukutsuka, Takeshi Abe
Cobalt-based layered perovskite oxychlorides Sr2CoO3Cl and Sr3Co2O5Cl2 exhibit high oxygen electrocatalytic activity compared to conventional lanthanum cobalt-based perovskite oxides. The enhanced oxygen electrocatalytic activity can be attributed to the upshifted O p-band center relative to the Fermi level caused by the incorporation of chloride anion into oxygen sites.
February 15, 2017: Chemical Communications: Chem Comm
Quinten A Akkerman, Eros Radicchi, Sungwook Park, Francesca Nunzi, Edoardo Mosconi, Filippo De Angelis, Rosaria Brescia, Prachi Rastogi, Mirko Prato, Liberato Manna
We have developed a colloidal synthesis of nearly monodisperse nanocrystals of pure Cs4PbX6 (X = Cl, Br, I) and their mixed halide compositions, with sizes ranging from 9 nm to 37 nm. The optical absorption spectra of these nanocrystals display a sharp, high energy peak due to transitions between states localized in individual PbX64- octahedra. These spectral features are insensitive to the size of the particles and in agreement with the features of the corresponding bulk materials. Samples with mixed halide composition exhibit absorption bands that are intermediate in spectral position between those of the pure halide compounds...
February 14, 2017: Nano Letters
Lili Wang, Nicholas E Williams, Edward William Malachosky, John P Otto, Dugan Hayes, Ryan E Wood, Philippe Guyot-Sionnest, Gregory S Engel
Colloidal perovskite nanocrystals support bright, narrow photoluminescence tunable over the visible spectrum. However, bandgap tuning of these materials remains limited to laboratory-scale syntheses. In this work, we present polar-solvent-free ligand-mediated transport synthesis of high quality organic-inorganic perovskite nanocrystals under ambient conditions with photoluminescence quantum yields up to 97%. Our synthesis employs a ligand-mediated transport mechanism that circumvents the need for exquisite external control (e...
February 14, 2017: ACS Nano
Wei Chen, Leiming Xu, Xiyuan Feng, Jiansheng Jie, Zhubing He
A series of metal acetylacetonates produced by a full low-temperature (below 100 °C) process are successfully employed to obtain both "multistable" and high-performance planar-inverted perovskite solar cells. All the three kinds of champion cells in small area exhibit over 18% in conversion-efficiency with negligible hysteresis, along with above 16% in conversion-efficiency for planar PSCs in an aperture area of over 1 cm(2) .
February 14, 2017: Advanced Materials
Tsung Yu Hsieh, Chi Kai Huang, Tzu-Sen Su, Cheng-You Hong, Tzu-Chien Wei
Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the seconds step, i.e. methlyammonium iodide immersion in the morphological, structural, optical and photovoltaic evolution, is extensively investigated...
February 14, 2017: ACS Applied Materials & Interfaces
Chao Dong, Zi-Wei Liu, Jie-Yu Liu, Wei-Chao Wang, Lan Cui, Rui-Chun Luo, Hui-Long Guo, Xue-Li Zheng, Shi-Zhang Qiao, Xi-Wen Du, Jing Yang
Manganese-based oxides have exhibited high promise as noncoinage alternatives to Pt/C for catalyzing oxygen reduction reaction (ORR) in basic solution and a mix of Mn(3+/4+) valence is believed to be vital in achieving optimum ORR performance. Here, it is proposed that, distinct from the most studied perovskites and spinels, Mn-based mullites with equivalent molar ratio of Mn(3+) and Mn(4+) provide a unique platform to maximize the role of Mn valence in facile ORR kinetics by introducing modest content of oxygen deficiency, which is also beneficial to enhanced catalytic activity...
February 13, 2017: Small
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