Browsing by Author "Wu, Hung-Ruei"

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Grain structure control and greatly enhanced carrier transport by CH3NH3PbCl3 interlayer in two-step solution processed planar perovskite solar cells
(2016-11)
Chern, Yann-Cherng
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Chen, Yen-Chu
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Wu, Hung-Ruei
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Zan, Hsiao-Wen
;
Meng, Hsin-Fei
We report that the use of a CH3NH3PbCl3 interlayer onto the PEDOT:PSS layer in the two-step solution deposition of CH3NH3PbCl3 for planar p-i-n type perovskite solar cells (PSCs) can lead to a dramatic enhancement of short-circuit current density (J(SC)) by 52.8% from 13.07 mA cm(-2) to 19.98 mA cm(-2). While the absorption and thus the composition of the perovskite layers remain unchanged, Incident photon-to-current efficiency (IPCE) measurement results reveal much enhanced carrier transport, which in turn can be correlated to the larger and more columnar grain structure in the perovskite layer with the use of the CH3NH3PbCl3 interlayer. On the other hand, the two-step solution processed perovskite layers without the CH3NH3PbCl3 interlayer exhibit smaller and more cross-hatching grain structure and yield significantly smaller J(SC). Therefore our results revealed clearly that the insertion of CH3NH3PbCl3 interlayer, which affects the nucleation dynamics, may control the grain structure of the two-step solution processed perovskite layers and improve dramatically the photovoltaic performance of the resultant planar p-i-n type PSCs. Our CH3NH3PbCl3 interlayer may thus serve as an effective method for p-i-n PSCs to achieve high J(SC) with thicker perovskite layer. (C) 2016 Elsevier B.V. All rights reserved.
Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation
(2015-08-01)
Chern, Yann-Cherng
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Wu, Hung-Ruei
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Chen, Yen-Chu
;
Zan, Hsiao-Wen
;
Meng, Hsin-Fei
A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm x 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 +/- 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.