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Proceedings Paper

Efficient planar-mixed heterojunction photovoltaic device based on subphthalocyanine:C70 structure
Author(s): Wei-Cheng Su; Shun-Wei Liu; Ching-Wen Cheng; Chia-Chang Chou; Jia-Cing Huang; Chih-Chien Lee
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Paper Abstract

In this report, we demonstrate an efficient planar-mixed heterojunction organic photovoltaic (OPV) device employing a mixed structure of subphthalocyanine (SubPc) donor and C70 acceptor. Compared to a SubPc:C60 cell, the SubPc:C70 cell exhibits high performance with a fill factor (FF) of 52%, short-circuit current density (JSC) of 8.8 mA/cm2, open-circuit voltage (VOC) of 1 V, and power conversion efficiency of 4.6% under air-mass 1.5 G illumination (1 sun). The high VOC is mainly due to the wide interface gap between SubPc and C70 as in the SubPc:C60 device. On comparing the absorption spectra of C70 and C60, C70 shows the higher absorption coefficient and wider absorption band, leading to the significantly improved JSC. Moreover, the FF of the device using C70 is enhanced to 52%; by comparison it is 45% when using C60. In order to understand this phenomenon, the space-charge limited current is measured for estimating the carrier mobility of SubPc, C70, and C60. It reveals that the electron mobility of C70 is lower than that of C60 by orders of magnitude but is close to the hole mobility of SubPc. As a result, a better charge balance condition is achieved when SubPc is blended with C70 and therefore a higher FF is obtained. Consequently, C70 seems to be a more suitable acceptor for the mixed structure to develop a highly efficient OPV device due to the improvements in both electrical and optical properties.

Paper Details

Date Published: 13 September 2012
PDF: 7 pages
Proc. SPIE 8477, Organic Photovoltaics XIII, 84771E (13 September 2012); doi: 10.1117/12.929562
Show Author Affiliations
Wei-Cheng Su, National Taiwan Univ. of Science and Technology (Taiwan)
Shun-Wei Liu, Ming Chi Univ. of Technology (Taiwan)
Ching-Wen Cheng, National Taiwan Univ. of Science and Technology (Taiwan)
Chia-Chang Chou, National Taiwan Univ. of Science and Technology (Taiwan)
Jia-Cing Huang, National Taiwan Univ. of Science and Technology (Taiwan)
Chih-Chien Lee, National Taiwan Univ. of Science and Technology (Taiwan)

Published in SPIE Proceedings Vol. 8477:
Organic Photovoltaics XIII
Zakya H. Kafafi; Christoph J. Brabec; Paul A. Lane, Editor(s)

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