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Zhaoran Xu

Bio: Zhaoran Xu is an academic researcher from Nanjing University. The author has contributed to research in topics: Crystalline silicon & Silicon. The author has an hindex of 9, co-authored 13 publications receiving 1120 citations. Previous affiliations of Zhaoran Xu include University of California, Berkeley & Lawrence Berkeley National Laboratory.

Papers
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TL;DR: This study reports the successful fabrication of all-inorganic PSCs without any labile or expensive organic components, and opens the door for next-generation P SCs with long-term stability under harsh conditions, making practical application of Pscs a real possibility.
Abstract: The research field on perovskite solar cells (PSCs) is seeing frequent record breaking in the power conversion efficiency (PCE). However, organic–inorganic hybrid halide perovskites and organic additives in common hole-transport materials (HTMs) exhibit poor stability against moisture and heat. Here we report the successful fabrication of all-inorganic PSCs without any labile or expensive organic components. The entire fabrication process can be operated in ambient environment without humidity control (e.g., a glovebox). Even without encapsulation, the all-inorganic PSCs present no performance degradation in humid air (90–95% relative humidity, 25 °C) for over 3 months (2640 h) and can endure extreme temperatures (100 and −22 °C). Moreover, by elimination of expensive HTMs and noble-metal electrodes, the cost was significantly reduced. The highest PCE of the first-generation all-inorganic PSCs reached 6.7%. This study opens the door for next-generation PSCs with long-term stability under harsh conditions,...

824 citations

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional magic-angle spinning NMR experiment using multiple-quantum coherences of half-integer quadrupolar nuclei was used to study 27Al sites in crystalline samples of leucite (KAlSi2O6), anorthite (CaAl2Si 2O8), and kyanite (Al 2SiO5), as well as CaAl2 Si2O8 glass and a magnesium aluminoborate glass.
Abstract: A new two-dimensional magic-angle spinning NMR experiment1,2 using multiple-quantum coherences of half-integer quadrupolar nuclei was used to study 27Al sites in crystalline samples of leucite (KAlSi2O6), anorthite (CaAl2Si2O8), and kyanite (Al2SiO5), as well as CaAl2Si2O8 glass and a magnesium aluminoborate glass In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced In the aluminoborate glass, peaks for sites with different Al coordination numbers are well separated The lack of such features in CaAl2Si2O8 glass rules out the presence of significant quantities of AlO5 and AlO6 groups

186 citations

Journal ArticleDOI
TL;DR: In this article, a high performance, low-temperature, electron-selective heterocontact is developed, comprised of a surface passivating a-Si:H layer, a protective TiOx interlayer, and a low work function LiFx/Al outer electrode.
Abstract: Development of new device architectures and process technologies is of tremendous interest in crystalline silicon (c-Si) photovoltaics to drive enhanced performance and/or reduced processing cost. In this regard, an emerging concept with a high-efficiency potential is to employ low/high work function metal compounds or organic materials to form asymmetric electron and hole heterocontacts. This Letter demonstrates two important milestones in advancing this burgeoning concept. First, a high-performance, low-temperature, electron-selective heterocontact is developed, comprised of a surface passivating a-Si:H layer, a protective TiOx interlayer, and a low work function LiFx/Al outer electrode. This is combined with a MoOx hole-selective heterocontact to demonstrate a cell efficiency of 20.7%, the highest value for this cell class to date. Second, we show that this cell passes a standard stability test by maintaining >95% of its original performance after 1000 h of unencapsulated damp heat exposure, indicating...

154 citations

Journal ArticleDOI
TL;DR: In this article, an integrated perovskite solar capacitor (IPSC) was realized by combining a solar cell and a supercapacitor in a single device, taking advantage of nanocarbon electrodes, the IPSCs possess a simple configuration, compact structure, and well matched operation voltage.
Abstract: Integrating energy harvesting devices with energy storage systems can realize a temporal buffer for local power generation and power consumption. In this manner, self-charging energy devices consisting of photovoltaic cells and energy storage units can serve as sustainable and portable distributed power sources that can concurrently generate and store electric energy without the need for external charging circuits. Herein, an integrated perovskite solar capacitor (IPSC) was realized by combining a perovskite solar cell (PSC) and a supercapacitor in a single device. Taking advantages of nanocarbon electrodes, the IPSCs possess a simple configuration, compact structure, and well-matched operation voltage. The IPSCs could be rapidly charged by different modes (including the photo-charging mode, galvanostatic-charging mode, and photoassisted-galvanostatic-charging mode), and showed a remarkable overall photo-chemical-electricity energy conversion efficiency as high as 7.1% in the photo-charging mode. Moreover, the IPSCs could work efficiently under weak light illumination. This study provides new insights for the design of novel integrative energy devices that combine the functions of solar power harvesting and electrochemical energy storage.

75 citations

Journal ArticleDOI
TL;DR: An efficient method to synthesize well-crystallized inorganic cesium lead halide perovskites with high yield and high reproducibility was proposed, and two-terminal photodetectors and all-inorganic perovSKite solar cells based on b-CsPbI3 were fabricated, exhibiting high performances.
Abstract: An efficient method to synthesize well-crystallized inorganic cesium lead halide perovskites (CsPbX3, X = I or Br) with high yield and high reproducibility was proposed. Notably, the as-prepared CsPbI3 in the yellow orthorhombic phase (y-CsPbI3) can be easily converted to the black cubic perovskite phase CsPbI3 (b-CsPbI3) after thermal annealing. Furthermore, two-terminal photodetectors and all-inorganic perovskite solar cells based on b-CsPbI3 were fabricated, exhibiting high performances.

69 citations


Cited by
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Bo Li1, Yanan Zhang1, Lin Fu1, Tong Yu1, Shujie Zhou1, Luyuan Zhang1, Longwei Yin1 
TL;DR: In this article, a polyvinylpyrrolidone (PVP)-induced surface passivation engineering is reported to synthesize extra-long-term stable cubic cesium lead iodides (CsPbI3) for commercial perovskite solar cells.
Abstract: Owing to inevitable thermal/moisture instability for organic–inorganic hybrid perovskites, pure inorganic perovskite cesium lead halides with both inherent stability and prominent photovoltaic performance have become research hotspots as a promising candidate for commercial perovskite solar cells. However, it is still a serious challenge to synthesize desired cubic cesium lead iodides (CsPbI3) with superior photovoltaic performance for its thermodynamically metastable characteristics. Herein, polymer poly-vinylpyrrolidone (PVP)-induced surface passivation engineering is reported to synthesize extra-long-term stable cubic CsPbI3. It is revealed that acylamino groups of PVP induce electron cloud density enhancement on the surface of CsPbI3, thus lowering surface energy, conducive to stabilize cubic CsPbI3 even in micrometer scale. The cubic-CsPbI3 PSCs exhibit extra-long carrier diffusion length (over 1.5 μm), highest power conversion efficiency of 10.74% and excellent thermal/moisture stability. This result provides important progress towards understanding of phase stability in realization of large-scale preparations of efficient and stable inorganic PSCs.

504 citations

Journal ArticleDOI
TL;DR: In this paper, the authors take familiar inorganic oxide glasses and non-oxide glasses and the liquids from which they derive to review the current understanding of their atomic structure, ranging from the local environments of individual atoms to the long-range order which can cover many interatomic distances.
Abstract: We take familiar inorganic oxide glasses and non-oxide glasses and the liquids from which they derive to review the current understanding of their atomic structure, ranging from the local environments of individual atoms to the long-range order which can cover many interatomic distances. The structural characteristics of important glasses and melts, like silicates, borates, alumino-silicates, halides and chalcogenides, are drawn from the results of recent spectroscopy and scattering experiments. The techniques include Nuclear Magnetic Resonance (NMR) and X-ray Absorption Fine Structure (XAFS), Neutron Scattering (NS) and Small- and Wide-angle X-ray Scattering measurements (SAXS/WAXS), and are often combined with computer simulation experiments in order to obtain detailed images of structure and diffusion in the glassy as well as in the molten state. We then review the current understanding of relaxation in glasses, liquids and polyamorphic states. This includes phenomenological models and theories of rela...

477 citations

Journal ArticleDOI
01 Nov 1997-Nature
TL;DR: In this paper, the relative abundance of these weakly bonded NBOs is determined in determining the thermodynamic and dynamical properties of aluminosilicate glasses and melts, and the results require a reassessment of the high-temperature liquid properties that control many processes in the Earth and in industry.
Abstract: The most common of man-made glasses have aluminosilicate compositions, and such glasses also form from rapidly cooling magmas1. Oxygen is the most abundant element in these materials, where it occupies either ‘bridging’ (BO) or ‘non-bridging’ (NBO) sites. BOs link two AlO4 or SiO4 tetrahedra, thereby providing strong, long-lived bonds between the smallest structural units of the aluminosilicate network. NBOs provide a relatively weak connection between one tetrahedral cation (Al or Si) and one or more network modifier cations — such as Ca2+or Na+ — that are not an integral part of the tetrahedral network. The relative abundance of these weakly bonded NBOs is critical in determining the thermodynamic and dynamical properties of aluminosilicate glasses and melts1,2,3. For glasses of ‘tectosilicate’ composition, where the charge of the modifier cation equals the number of aluminium atoms (as in NaAlSi3O8 or CaAl2Si2O8), the conventional view of glass structure is that only BOs are present1,4. Here we present experimental observations that contradict this view. Our NMR measurements of CaAl2Si2O8, which determine directly the relative abundances of BO and NBO, indicate that a considerable amount of NBO can be present in a tectosilicate glass. These excess NBOs will increase the entropy and heat capacity of the corresponding liquid and decrease its viscosity, as well as modifying flow and diffusion mechanisms2,3. As the most common rhyolitic magmas and the molten precursors of glass ceramics have near-tectosilicate compositions1,4, our results require a reassessment of the high-temperature liquid properties that control many processes in the Earth and in industry.

444 citations

Journal ArticleDOI
TL;DR: In this paper, a compositional engineering approach via incorporating Bi3+ in CsPbI3 to stabilize the α-phase at room temperature was introduced, which achieved a high PCE of 13.21% at an optimal condition (incorporation of 4 mol % Bi3+) and maintain 68% of the initial PCE for 168 h under ambient conditions without encapsulation.
Abstract: All-inorganic CsPbI3 perovskite is emerging to be an alternative light-harvesting material in solar cells owing to the enhanced stability and comparable photovoltaic performance compared to organic–inorganic hybrid perovskites. However, the desirable black phase α-CsPbI3 is not stable at room temperature and degrades rapidly to a nonperovskite yellow phase δ-CsPbI3. Herein, we introduce a compositional engineering approach via incorporating Bi3+ in CsPbI3 to stabilize the α-phase at room temperature. Fully inorganic solar cells based on the Bi-incorporated α-CsPb1–xBixI3 compounds demonstrate a high PCE of 13.21% at an optimal condition (incorporation of 4 mol % Bi3+) and maintain 68% of the initial PCE for 168 h under ambient conditions without encapsulation. This is the first attempt of partial substitution of the “B”-site of the perovskite to stabilize the α-CsPbI3, which paves the way for further developments of such perovskites and other optoelectronic devices.

436 citations

Journal ArticleDOI
TL;DR: This study anchored CsPbBr3 QDs on NHx -rich porous g-C3 N4 nanosheets (PCN) to construct the composite photocatalysts via N-Br chemical bonding to open up new possibilities of using halide perovskite QDs for photoc atalytic application.
Abstract: Halide perovskite quantum dots (QDs) have great potential in photocatalytic applications if their low charge transportation efficiency and chemical instability can be overcome To circumvent these obstacles, we anchored CsPbBr3 QDs (CPB) on NHx -rich porous g-C3 N4 nanosheets (PCN) to construct the composite photocatalysts via N-Br chemical bonding The 20 CPB-PCN (20 wt % of QDs) photocatalyst exhibits good stability and an outstanding yield of 149 μmol h-1 g-1 in acetonitrile/water for photocatalytic reduction of CO2 to CO under visible light irradiation, which is around 15 times higher than that of CsPbBr3 QDs This study opens up new possibilities of using halide perovskite QDs for photocatalytic application

428 citations