Browsing by Author "Chiou, Ding-Wen"

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A look into the origin of shunt leakage current of Cu(In,Ga)Se-2 solar cells via experimental and simulation methods
(2013-10-01)
Liao, Yu-Kuang
;
Kuo, Shou-Yi
;
Hsieh, Ming-Yang
;
Lai, Fang-I
;
Kao, Ming-Hsuan
This study investigates how to apply space-charge-limited (SCL) current to describe shunt leakage current in a CIGS solar cell. Possible factors inducing SCL current have been observed through conductive atomic force microscopy (C-AFM), which supports the SCL current theory, describing the shunt current of a CIGS solar cell. In simulations derived from experimental data, deviation of dark IV curves is due to flaws in the real device. These flaws are absent in simulation, but investigation verifies the characteristics of SCL current component's experimental IV curves within shunt leakage current. A device with a metal/CIGS/metal structure could simulate SCL current and confirm its characteristics. Such a simulated structure, representing flaws inserted into a CIGS solar cell, generates the same dark-current behavior revealed in experimental dark IV curves. This study investigates the response of dark current to varying sizes of the flaw within the CIGS solar cell. (C) 2013 Elsevier B.V. All rights reserved.
Observation of unusual optical transitions in thin-film Cu(In,Ga)Se-2 solar cells
(2012-11-05)
Liao, Yu-Kuang
;
Kuo, Shou-Yi
;
Lin, Woei-Tyng
;
Lai, Fang-I
;
Hsieh, Dan-Hua
In this paper, we examine photoluminescence spectra of Cu(In,Ga)Se-2 (CIGS) via temperature-dependent and power-dependent photoluminescence (PL). Donor-acceptor pair (DAP) transition, near-bandedge transition were identified by their activation energies. S-shaped displacement of peak position was observed and was attributed to carrier confinement caused by potential fluctuation. This coincides well with the obtained activation energy at low temperature. We also present a model for transition from V-Se to V-In and to V-Cu which illustrates competing mechanisms between DAPs recombinations. (C) 2012 Optical Society of America