Non-antireflective scheme for efficiency enhancement of Cu(In,Ga)Se 2 nanotip array solar cells

Yu Kuang Liao, Yi Chung Wang, Yu Ting Yen, Chia Hsiang Chen, Dan Hua Hsieh, Shih Chen Chen, Chia Yu Lee, Chih Chung Lai, Wei Chen Kuo, Jenh-Yih Juang, Kaung-Hsiung Wu, Shun-Jen Cheng, Chih Huang Lai, Fang I. Lai, Shou Yi Kuo, Hao-Chung Kuo*, Yu Lun Chueh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

We present systematic works in characterization of CIGS nanotip arrays (CIGS NTRs). CIGS NTRs are obtained by a one-step ion-milling process by a direct-sputtering process of CIGS thin films (CIGS TF) without a postselenization process. At the surface of CIGS NTRs, a region extending to 100 nm in depth with a lower copper concentration compared to that of CIGS TF has been discovered. After KCN washing, removal of secondary phases can be achieved and a layer with abundant copper vacancy (VCu) was left. Such compositional changes can be a benefit for a CIGS solar cell by promoting formation of Cd-occupied Cu sites (CdCu) at the CdS/CIGS interface and creates a type-inversion layer to enhance interface passivation and carrier extraction. The raised VCu concentration and enhanced Cd diffusion in CIGS NTRs have been verified by energy dispersive spectrometry. Strengthened adhesion of Al:ZnO (AZO) thin film on CIGS NTRs capped with CdS has also been observed in SEM images and can explain the suppressed series resistance of the device with CIGS NTRs. Those improvements in electrical characteristics are the main factors for efficiency enhancement rather than antireflection.

Original languageEnglish
Pages (from-to)7318-7329
Number of pages12
JournalACS Nano
Volume7
Issue number8
DOIs
StatePublished - 27 Aug 2013

Keywords

  • CIGS solar cell
  • Cd diffusion
  • copper vacancy
  • direct sputtering
  • nanotip arrays

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