Significant Passivation Effect of Cu(In, Ga)Se2 Solar Cells via Back Contact Surface Modification Using Oxygen Plasma. Issue 3 (18th January 2021)

• Record Type: Journal Article
• Authors: Zeng, Longlong; Zeng, Chunhong; Liang, Yunfeng; Yuan, Ye; Yan, Genghua; Hong, Ruijiang
• Is Part Of: Solar RRL. Volume 5:Issue 3(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-18
• Subjects: back surface passivation mechanism -- crystallization stratification -- Cu(In -- Ga)Se2 solar cells -- molybdenum oxide -- oxygen plasma; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202000572
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Molybdenum back contact plays a significant role in chalcopyrite Cu(In, Ga)Se2 (CIGS) solar cells. A molybdenum oxide intermediate layer is applied to optimize the back contact from the aspect of absorber crystal growth regulation and back surface field reconstruction. A novel molybdenum oxide preparation method is introduced through oxygen plasma treatment of the molybdenum layer. CIGS film is obtained by sputtering from a quaternary target with post‐selenization. The shortage of Cu and Se in the middle of the absorption layer causes crystallization stratification. A bidirectional regulation method for controlling intermediate fine grains is proposed. Superior crystallinity is produced to facilitate carriers' transport and reduce recombination at grain boundaries. Back passivation is achieved by forming a reverse p–n junction on the back surface. Despite the formation of this reverse junction, the efficiency of the device is still improved because the transport of holes is assisted by the molybdenum oxide's gap states. Thus, back surface recombination is effectively reduced by back passivation, leading to the increase in open‐circuit voltage ( V oc ) and fill factor (FF). The power conversion efficiency of treated solar cells increases by 34.1%. An innovative direction is proposed to optimize the back contact of CIGS solar cells in this study. Abstract : Through the modification of molybdenum oxide prepared by oxygen plasma, crystallization stratification is inhibited and back contact is optimized through a reverse p–n junction. The transport of holes is assisted by the molybdenum oxide's gap states. The efficiency of Cu(In, Ga)Se2 (CIGS) solar cell sputtering from a quaternary target with oxygen plasma treatment increases by 34.1%.