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Li F.,National Renewable Energy Laboratory | Zhu W.,National Renewable Energy Laboratory | Bao C.,National Renewable Energy Laboratory | Yu T.,National Renewable Energy Laboratory | And 7 more authors.
Chemical Communications | Year: 2016

Laser irradiation as a rapid crystallization approach was successfully introduced to prepare homogeneous, dense-grained CH3NH3PbI3 films. Planar-heterojunction solar cells employing these high-quality films showed the optimal efficiency of 17.8% with a remarkably high open-circuit voltage of 1.146 V. © The Royal Society of Chemistry 2016. Source


Zhu W.,National Renewable Energy Laboratory | Bao C.,National Renewable Energy Laboratory | Li F.,National Renewable Energy Laboratory | Yu T.,National Renewable Energy Laboratory | And 10 more authors.
Nano Energy | Year: 2016

A facile halide exchange route based on CH3NH3Br solution post-treatment has been successfully employed to transform the two-step spin-coated CH3NH3PbI3 films into the CH3NH3PbI3-xBrx films, whose morphologies and compositions could be modified simultaneously. With the increase of CH3NH3Br solution concentration, the CH3NH3PbI3-xBrx films exhibited increased grain size, prolonged charge carrier lifetime, and enlarged bandgap with slightly reduced light absorption compared with the parent CH3NH3PbI3 film. The mesostructured perovskite solar cells based on the CH3NH3PbI3-xBrx films yielded the optimal power conversion efficiency (PCE) of 14.25%, which is much higher than that of device with the parent CH3NH3PbI3 film. In particular, the device based on the CH3NH3PbI3-xBrx film retained up to 93% of its original PCE after exposed to air for 14 days without any encapsulation, presenting a favorable stability. Our work suggests a novel and attractive way to fabricate high-performance perovskite solar cells with excellent stability. © 2015 Elsevier Ltd. Source


Zhu W.,National Renewable Energy Laboratory | Bao C.,National Renewable Energy Laboratory | Li F.,National Renewable Energy Laboratory | Zhou X.,National Renewable Energy Laboratory | And 7 more authors.
Chemical Communications | Year: 2015

A dense and homogenous flat wide-bandgap (1.75 eV) CH3NH3PbI2.1Br0.9 perovskite film was prepared via a facile halide exchange route. The planar-heterojunction solar cell shows an optimal power conversion efficiency of 12.67% with negligible current hysteresis due to the film's large grains and vertically oriented grain boundaries. © 2015 The Royal Society of Chemistry. Source


Wu B.,Nanjing University | Zhao M.,Nanjing University | Shi W.,Dalian Sunrise Power Co. | Liu W.,Nanjing University | And 8 more authors.
International Journal of Hydrogen Energy | Year: 2014

Accelerated stress tests (ASTs) were performed to study the degradation mechanism of Nafion/PTFE composite membrane in PEM fuel cell with intensive RH cycling and load cycling. It was recognized that the edge of membrane electrode assembly (MEA) should be carefully treated to prevent the immediate failure for excessive or non-uniform mechanical stress mainly caused by RH cycling in the early period of ASTs. A long accelerated life (over 1000 h) was obtained for MEA with an edge protection and a hot-pressing process along with a low hydrogen permeation current. In addition, the decay of open circuit voltage, the fluoride emission rate (FER) from cathode side and the polarization curves were also monitored during the test. It was verified that the chemical degradation of membrane occurred inevitably caused by radical attack (HO, HO2 and H2O2) due to the intensification of gas mutual permeation. Membrane thinning, Pt particles gathering along the interfaces, even ionomer disappearing at cathode side could be observed from TEM and SEM results. Besides, open circuit voltage under H2/N2 atmosphere of MEA was confirmed to be a rapid diagnose tool of membrane physical condition. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Zhou P.,National Renewable Energy Laboratory | Gao H.L.,Nanjing University | Yan S.C.,Nanjing University | Yan S.C.,Jiangsu Key Laboratory for Nano Technology | And 3 more authors.
Dalton Transactions | Year: 2016

Functional hollow nanomaterials are of great interest due to their unique physical-chemical properties. Oxynitride photocatalysts are a kind of promising material for solar energy conversion. However, nanoscale design of hollow oxynitrides was difficult to achieve due to the thermal instability of oxide precursors at high temperature. Here, single crystal zinc gallium oxynitride nanotubes were successfully synthesized via the Kirkendall effect with ZnO nanorods and Ga2O3 nanosheets as precursors, which can be attributed to the high diffusion rate of ZnO and the high melting point of oxynitride. Enhanced photocatalytic performance in CO2 reduction was achieved over the as-prepared ZnGaNO nanotubes, due to their higher specific surface area and less recombination of the photogenerated carriers. These results are expected to provide new guidance in the design and preparation of highly efficient nano-scaled oxynitride photocatalysts. © The Royal Society of Chemistry 2016. Source

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