title: Trade-offs of the opto-electrical properties of a-Si:H solar cells based on MOCVD BZO films.
abstract: Boron-doped zinc oxide (BZO) films, deposited by metal-organic chemical vapor deposition (MOCVD), have been widely used as front electrodes in thin-film solar cells due to their native pyramidal surface structure, which results in efficient light trapping. This light trapping effect can enhance the short-circuit current density (Jsc) of solar cells. However, nanocracks or voids in the silicon active layer may form when the surface morphology of the BZO is too sharp; this usually leads to degraded electrical properties of the cells, such as open-circuit voltage (Voc) and the fill factor (FF), which in turn decreases efficiency (Eff) [Bailat et al., Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on. IEEE, 2006, vol. 2, pp. 1533-1536]. In this paper, an etching and coating method was proposed to modify the sharp "pyramids" on the surface of the BZO films. As a result, an evident enhancement was achieved for these modified, BZO-based cells' Voc, FF, and Eff, although the Jsc exhibited a small decrease. In order to increase the Jsc and maintain the improved electrical properties (Voc, FF) of the cell, a thin BZO coating, deposited by MOCVD, was introduced to coat the sputtering-treated BZO film. Finally, we optimized the trade-off among the Voc, FF, and Jsc, that is, we identified a regime with an increase of the Jsc as well as a further improvement of the other electrical properties.
authors.affiliation: Institute of Photo Electronic Thin Film Devices and Technology of Nankai University, Key Laboratory of Photoelectronic Thin Film Devices and Technology, Tianjin 300071, P. R. China. xdzhang@nankai.edu.cn.
authors.forename: Ze
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiao-dan
authors.initials: XD
authors.lastname: Zhang
authors.forename: Jun-hui
authors.initials: JH
authors.lastname: Liang
authors.forename: Jia
authors.initials: J
authors.lastname: Fang
authors.forename: Xue-jiao
authors.initials: XJ
authors.lastname: Liang
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: De-kun
authors.initials: DK
authors.lastname: Zhang
authors.forename: Xin-liang
authors.initials: XL
authors.lastname: Chen
authors.forename: Qian
authors.initials: Q
authors.lastname: Huang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao