Open Access Nano Express

Selective emitter using a screen printed etch barrier in crystalline silicon solar cell

Kyuwan Song1, Bonggi Kim1, Hoongjoo Lee3, Youn-Jung Lee1, Cheolmin Park2, Nagarajan Balaji2, Minkyu Ju1, Jaewoo Choi1 and Junsin Yi12*

Author affiliations

1 School of Information and Communication Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, 440-746, South Korea

2 Department of Energy Science, Sungkyunkwan University, Suwon, 440-746, South Korea

3 Department of Computer System Engineering, Sangmyung University, Cheonan, 330-720, South Korea

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Citation and License

Nanoscale Research Letters 2012, 7:410  doi:10.1186/1556-276X-7-410

Published: 23 July 2012

Abstract

The low level doping of a selective emitter by etch back is an easy and low cost process to obtain a better blue response from a solar cell. This work suggests that the contact resistance of the selective emitter can be controlled by wet etching with the commercial acid barrier paste that is commonly applied in screen printing. Wet etching conditions such as acid barrier curing time, etchant concentration, and etching time have been optimized for the process, which is controllable as well as fast. The acid barrier formed by screen printing was etched with HF and HNO3 (1:200) solution for 15 s, resulting in high sheet contact resistance of 90 Ω/sq. Doping concentrations of the electrode contact portion were 2 × 1021 cm−3 in the low sheet resistance (Rs) region and 7 × 1019 cm−3 in the high Rs region. Solar cells of 12.5 × 12.5 cm2 in dimensions with a wet etch back selective emitter Jsc of 37 mAcm−2, open circuit voltage (Voc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on Voc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with Jsc of 36.90 mAcm−2, Voc of 625.7 mV, and efficiency of 17.60%.

Keywords:
Crystalline solar cell; Wet etch back; Selective emitter; Acid barrier