The Formation Mechanism of Cu(In0.7Ga0.3)Se2 Nanoparticles and the Densification Trajectory of the Se-Rich Quaternary Target by Hot Pressing

• Main Authors: Qiang Ma, Weijia Zhang, Zhaoyi Jiang, Denghao Ma, Yulong Zhang, Chaoqun Lu, Zhiqiang Fan
• Format: Article
• Language: English
• Published: MDPI AG 2018-03-01
• Series: Crystals
• Subjects: Se-rich target; hot pressing; CIGS; formation mechanism
• Online Access: http://www.mdpi.com/2073-4352/8/3/135
• ISSN: 2073-4352

In this paper, a method to obtain the CuInGaSe2 (CIGS) absorber layer with an appropriate selenium content is put forward, in which a Se-rich target is used to deposit a CIGS thin-film and this film is annealed in a Se-free inert atmosphere. The key issue of this method is the preparation of a Se-rich target with a homogeneous composition and a high-density. The formation mechanism of CuInSe2 and CuGaSe2 is investigated and the results point to the intermediate phase Cu2−xSe playing a role of a nucleation core. The sintering densification trajectory of the target with the addition of extra selenium is researched. Additionally, an effective way to avoid the sintering defects is proposed. Finally, a conversion efficiency of 11.2% for the CIGS solar cell is reached by sputtering from the obtained Se-rich target.