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Sudipta Seth, Anunay Samanta
Zero-dimensional (0-D) perovskites and perovskite-related materials are an emerging class of optoelectronic materials exhibiting strong excitonic properties and quite often, high photoluminescence (PL) in the solid state. Here we highlight two different classes of 0-D perovskites with contrasting structural and optical properties focusing mainly on the less explored, but rapidly growing bulk quantum materials termed as 0-D perovskite related materials (0-D PRMs), whose PL properties are quite intriguing and a topic of recent debate...
December 14, 2017: Journal of Physical Chemistry Letters
Qiuhong Cui, Guillermo C Bazan
Two essential structural elements define a class of materials called conjugated polyelectrolytes (CPEs). The first is a polymer framework with an electronically delocalized, π-conjugated structure. This component allows one to adjust desirable optical and electronic properties, for example the range of wavelengths absorbed, emission quantum yields, electron affinity, and ionization potential. The second defining feature is the presence of ionic functionalities, which are usually linked via tethers that can modulate the distance of the charged groups relative to the backbone...
December 14, 2017: Accounts of Chemical Research
Navendu Mondal, Apurba De, Anunay Samanta
Excitation of semiconductor quantum dots (QDs) by photons possessing energy higher than the band-gap creates a hot electron-hole pair, which releases its excess energy as waste heat or under certain conditions (when hν > 2Eg) produces multiple excitons. Extraction of these hot carriers and multiple excitons is one of the key strategies for enhancing the efficiency of QD-based photovoltaic devices. However, this is a difficult task as competing carrier cooling and relaxation of multiple excitons (through Auger recombination) are ultrafast processes...
December 13, 2017: Nanoscale
Shuying Wang, Xiaona Huang, Haoxuan Sun, Chunyang Wu
Inverted planar perovskite solar cells (PSCs), which are regarded as promising devices for new generation of photovoltaic systems, show many advantages, such as low-temperature film formation, low-cost fabrication, and smaller hysteresis compared with those of traditional n-i-p PSCs. As an important carrier transport layer in PSCs, the hole transport layer (HTL) considerably affects the device performance. Therefore, HTL modification becomes one of the most critical issues in improving the performance of PSCs...
December 13, 2017: Nanoscale Research Letters
Shinya Tsukada, Kenji Ohwada, Hidehiro Ohwa, Shigeo Mori, Seiji Kojima, Naohiko Yasuda, Hikaru Terauchi, Yukikuni Akishige
Relaxor ferroelectrics show substantial responses to electric fields. The key difference from normal ferroelectrics is a temperature-dependent inhomogeneous structure and its dynamics. The lead-based complex perovskite Pb(In1/2Nb1/2)O3 is an intriguing system in which the inhomogeneous structure can be controlled by thermal treatment. Herein, we report investigations of the phase transitions in single crystals of Pb(In1/2Nb1/2)O3 via changing the degree of randomness in which In and Nb occupy the B site of the ABO3 perovskite structure...
December 13, 2017: Scientific Reports
Seong Ryul Pae, Segi Byun, Jekyung Kim, Minkyu Kim, Issam Gereige, Byungha Shin
Recently, the trend in inverted hybrid perovskite solar cells (PVSCs) has been to utilize NiOx as hole transport layers. However, the majority of reported solution-processed NiOx films require a high-temperature thermal annealing process which is unfavorable for large-scale manufacturing and suffers from lack of uniformity. We report, for the first time, e-beam evaporation as a low-temperature, vacuum process for the deposition of NiOx hole transport layers for PVSCs. Device characterization shows that efficiency is on par with solution-processed methods, the highest efficiency at 15...
December 13, 2017: ACS Applied Materials & Interfaces
You-Hyun Seo, Eun-Chong Kim, Se-Phin Cho, Seok-Soon Kim, Seok-In Na
In this data article, we introduced the hysteresis of planar perovskite solar cells (PSCs) fabricated using dimethylformamide (DMF), gamma-butyrolactone (GBL), methyl-2-pyrrolidinone (NMP), dimethylsulfoxide (DMSO), DMF-DMSO, GBL-DMSO and NMP-DMSO as perovskite precursor solutions according to different scan directions, sweep times, and current stability. The hysteresis analyses of the planar PSCs prepared with a glass-ITO /NiOX/perovskite /PC61BM/BCP/Ag configuration were measured with Keithley 2400 source meter unit under 100 mW/cm2 (AM 1...
February 2018: Data in Brief
Jingxiu Yang, Peng Zhang, Su-Huai Wei
Cs2AgBiBr6 was proposed as one of the inorganic, stable, and non-toxic replacement of the methylammonium lead halides (CH3NH3PbI3, which is currently considered as one of the most promising light-harvesting material for solar cells). However, the wide indirect band gap of Cs2AgBiBr6 suggests that its application in photovoltaics is limited. Here, using the first principle calculation, we show that by controlling the ordering parameter at the mixed sublattice, the band gap of Cs2AgBiBr6 can vary continuously from a wide indirect band gap of 1...
December 13, 2017: Journal of Physical Chemistry Letters
Jinlian Lu, Wei Luo, Junsheng Feng, Hongjun Xiang
Two-dimensional (2D) ferroelectricity have attracted much attention due to their applications in novel miniaturized devices such as non-volatile memories, field effect transistors and sensors. Since most of the commercial ferroelectric (FE) devices are based on ABO3 perovskite oxides, it is important to investigate the properties of 2D ferroelectricity in perovskite oxides thin films. Here, based on density functional theory (DFT) calculations, we find that there exist three kinds of in-plane ferroelectric states which originate from different microscopic mechanisms: (i) a proper FE state with the polarization along [110] due to the second-order Jahn-Teller effect related to the B ion with empty d-orbitals; (ii) a robust FE state with the polarization along [100] induced by the surface effect; (iii) a hybrid improper FE state with the polarization along [110] that is induced by the tri-linear coupling between two rotational modes and the A-site displacement...
December 12, 2017: Nano Letters
Gang Tang, Zewen Xiao, Hideo Hosono, Toshio Kamiya, Daining Fang, Jiawang Hong
Over the past few years, the development of lead-free and stabile perovskite absorbers with excellent performance has attracted extensive attention. Much effort has been devoted to screening and synthesizing this type of solar cell absorbers. Here, we present a general design strategy for designing the layered halide double perovskites Cs3+nM(II)nSb2X9+3n (M = Sn, Ge) with desired photovoltaic-relevant properties by inserting [MX6] octahedral layers, based on the principles of increased electronic dimensionality...
December 12, 2017: Journal of Physical Chemistry Letters
Junli Chang, Hong Chen, Hongkuan Yuan, Biao Wang, Xiaorui Chen
Organic-inorganic hybrid perovskites as new emerging functional materials stand out from numerous photovoltaic materials thanks to the unprecedentedly rapid improvement of their power conversion efficiency within a short period. To explore potentially more efficient photovoltaic candidates, the structural and electronic properties of FAxMA1-xPbI3 based on prototype MAPbI3 are investigated for superior performance. Specifically, structural relaxation is performed at the PBE+D2 level and the electronic and optical properties are investigated at the HSE + SOC level...
December 12, 2017: Physical Chemistry Chemical Physics: PCCP
Rafael Quintero-Bermudez, Randy P Sabatini, Marc Lejay, Oleksandr Voznyy, Edward H Sargent
Colloidal quantum dots (CQDs) enable low-cost, high-performance optoelectronic devices including photovoltaics, photodetectors, LEDs and lasers. Continuous-wave lasing in the near-infrared remains to be realized based on such materials; yet a solution-processed NIR laser would be of use in communications and interconnects. In infrared quantum dots, long-lived gain is hampered by a high rate of Auger recombination. Here we report the use of perovskite shells, grown on cores of IR-emitting PbS CQDs, and we reduce thereby the rate of Auger recombination by up to one order of magnitude...
December 11, 2017: ACS Nano
Tanaji P Gujar, Thomas Unger, Andreas Schönleber, Martina Fried, Fabian Panzer, Sander van Smaalen, Anna Köhler, Mukundan Thelakkat
We report a systematic investigation on the role of excess PbI2 content in CH3NH3PbI3 perovskite film properties, solar cell parameters and device storage stability. We used the CH3NH3I vapor assisted method for the preparation of PbI2-free CH3NH3PbI3 films under a N2 atmosphere. These pristine CH3NH3PbI3 films were annealed at 165 °C for different time intervals in a N2 atmosphere to generate additional PbI2 in these films. From XRD measurements, the excess of PbI2 was quantified. Detailed characterization using scanning electron microscopy, X-ray diffraction, UV-Visible and photoluminescence for continuous aging of CH3NH3PbI3 films under ambient condition (50% humidity) is carried out for understanding the influence of different PbI2 contents on degradation of the CH3NH3PbI3 films...
December 11, 2017: Physical Chemistry Chemical Physics: PCCP
Jun Wang, Junze Li, Qinghai Tan, Lei Li, Jianbing Zhang, Jianfeng Zang, Ping-Heng Tan, Jun Zhang, Dehui Li
Two-dimensional Ruddlesden-Popper type perovskites (2D perovskites) have recently attracted increasing attention. It is expected that 2D perovskite-based heterostructures can significantly improve the efficiency of the optoelectronic devices and extend the material functionalities; however, rational synthesis of such heterostructures has not been realized to date. Here, we report on a general low-temperature synthetic strategy for synthesis of 2D perovskite-based lateral and vertical (n-CH3(CH2)3NH3)2PbI4/(n-CH3(CH2)3NH3)2(CH3NH3)Pb2I7 heterostructures for the first time...
December 11, 2017: Journal of Physical Chemistry Letters
Wanyi Nie, Hsinhan Tsai, Jean-Christophe Blancon, Fangze Liu, Costas C Stoumpos, Boubacar Traore, Mikael Kepenekian, Olivier Durand, Claudine Katan, Sergei Tretiak, Jared Crochet, Pulickel M Ajayan, MercouriG Kanatzidis, Jacky Even, Aditya D Mohite
Hybrid perovskites are on a trajectory toward realizing the most efficient single-junction, solution-processed photovoltaic devices. However, a critical issue is the limited understanding of the correlation between the degree of crystallinity and the emergent perovskite/hole (or electron) transport layer on device performance and photostability. Here, the controlled growth of hybrid perovskites on nickel oxide (NiO) is shown, resulting in the formation of thin films with enhanced crystallinity with characteristic peak width and splitting reminiscent of the tetragonal phase in single crystals...
December 11, 2017: Advanced Materials
James A Dawson, Pieremanuele Canepa, Theodosios Famprikis, Christian Masquelier, M Saiful Islam
Solid electrolytes are generating considerable interest for all-solid-state Li-ion batteries to address safety and performance issues. Grain boundaries have a significant influence on solid electrolytes and are key hurdles that must be overcome for their successful application. However, grain boundary effects on ionic transport are not fully understood, especially at the atomic scale. The Li-rich anti-perovskite Li3OCl is a promising solid electrolyte, although there is debate concerning the precise Li-ion migration barriers and conductivity...
December 10, 2017: Journal of the American Chemical Society
Hongbo Cheng, Jun Ouyang, Yun-Xiang Zhang, David Ascienzo, Yao Li, Yu-Yao Zhao, Yuhang Ren
Dielectric capacitors have the highest charge/discharge speed among all electrical energy devices, but lag behind in energy density. Here we report dielectric ultracapacitors based on ferroelectric films of Ba(Zr0.2,Ti0.8)O3 which display high-energy densities (up to 166 J cm-3) and efficiencies (up to 96%). Different from a typical ferroelectric whose electric polarization is easily saturated, these Ba(Zr0.2,Ti0.8)O3 films display a much delayed saturation of the electric polarization, which increases continuously from nearly zero at remnant in a multipolar state, to a large value under the maximum electric field, leading to drastically improved recyclable energy densities...
December 8, 2017: Nature Communications
Honglei Wang, Shih-Chia Liu, Balasubramaniam Balachandran, Jiyoung Moon, Ross Haroldson, Zhitong Li, Artur Ishteev, Qing Gu, Weidong Zhou, Anvar Zakhidov, Walter Hu
Recently, solution-processed hybrid halide perovskite has emerged as promising materials for advanced optoelectronic devices such as photovoltaics, photodetectors, light emitting diodes and lasers. In the mean time, all-dielectric metasurfaces with high-index materials have attracted attention due to their low-loss and high-efficient optical resonances. Because of its tunable by composition band gap in the visible frequencies, organolead halide perovskite could serve as a powerful platform for realizing high-index, low-loss metasurfaces...
November 27, 2017: Optics Express
Junyi Gong, Yue Wang, Sheng Liu, Pan Zeng, Xilu Yang, Rongqing Liang, Qiongrong Ou, Xiang Wu, Shuyu Zhang
Halide perovskite materials have rapidly emerged as outstanding optoelectronic materials for solar cells, light-emitting diodes (LEDs), and lasers. Compared to hybrid organic-inorganic perovskites, all-inorganic perovskites have shown unique merits that may contribute to the ultimate goal of developing electrically-pumped lasers. In this paper, we demonstrate a distributed feedback (DFB) resonator using an all-inorganic perovskite thin film as the gain medium. The film has a gain coefficient of 161.1 cm-1 and a loss coefficient of 30...
November 27, 2017: Optics Express
Zhi-Gang Yu
Free-carrier absorption (FCA) in a semiconductor provides information about the band on which the free carriers reside, and in the classical limit, follows the $\omega^{-2}$ law with $\omega$ being the photon frequency. In hybrid organic-inorganic perovskites (HOIPs), the colossal Rashba effect (RE) results in a new band dispersion, characterized by wavevector $|{\bm k}|=k_0$ of band extremum and effective mass $m^*$. Here we show that the colossal RE in 2D HOIPs greatly enhances phonon-assisted FCA with a modified frequency dependence and induces a direct transition between the subbands with a resonance at $\hbar\omega=4R \equiv 2 \hbar^2 k^2_0/m^*$, which, under a magnetic field, exhibits a strong oscillatory magnetic circular dichroism (MCD)...
December 8, 2017: Journal of Physical Chemistry Letters
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