Behavior of Photocarriers in the Light-Induced Metastable State in the p-n Heterojunction of a Cu(In,Ga)Se2 Solar Cell with CBD-ZnS Buffer Layer

• DOI: 10.1021/acsami.6b05005
• Publication Date: 2016-08-05T17:08:57Z
• Authors: Woo-Jung Lee; Hye-Jung Yu; Jae-Hyung Wi; Dae-Hyung Cho; Won Seok Han; Jisu Yoo; Yeonjin Yi; Jung-Hoon Song; Yong-Duck Chung
• Keywords: Photocurrent; Chemical bath deposition; Metastability

We fabricated Cu(In,Ga)Se2 (CIGS) solar cells with a chemical bath deposition (CBD)-ZnS buffer layer grown varying ammonia concentrations in aqueous solution. The cell performance was degraded increasing concentration, due to actively dissolved Zn atoms during CBD-ZnS precipitation. These formed interfacial defect states, such as hydroxide species the film, and interstitial antisite defects at p-n heterojunction. After light/UV soaking, CIGS drastically improved, rise fill factor. With Zn-based layer, light soaking treatment containing blue photons induced metastable state enhanced performance. To interpret this effect, we suggest band structure model of heterojunction explain flow photocarriers under white initial state, then after soaking. determining factor is p+ an amount deep acceptor traps, located near surface. easily captures photoexcited electrons, when it becomes quasi-neutral, attracts holes. This alters barrier height controls photocurrent junction, values,