Implementation of Na diffusion layer at Cu2ZnSnSe4/Mo interface for flexible thin film solar cell fabricated on Ti foil by solid state selenization

• Published in: Current applied physics Vol. 20; no. 8; pp. 967 - 972
• Main Authors: Oh, Ji-A, Song, Yu Jin, Lim, Soo Yeon, Sriv, Tharith, Cheong, Hyeon Sik, Jeon, Chan-Wook
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2020; 한국물리학회
• Subjects: Cu2ZnSnSe4; Flexible solar cell; Selenization; Ti-foil; ZnSe; 물리학; Flexible solar cell; Na; Selenization; ZnSe; Ti-foil; Cu2ZnSnSe4
• ISSN: 1567-1739; 1878-1675; 1567-1739
• DOI: 10.1016/j.cap.2020.06.018

A Cu2ZnSnSe4 (CZTSe) photovoltaic absorber thin films were prepared using a 2-step selenization process on a Ti substrate including a Na precursor layer and a Na-free Ti substrate, and the effect of Na on the solar cell performance was compared. A CZTSe flexible solar cell fabricated on a Ti foil substrate exhibited an efficiency of 3.06%, which was less than half that of a solar cell fabricated on a soda lime glass substrate. This was attributed to the absence of Na and severe Zn crowding near the back contact. By depositing a 100‐nm-thick sodalime glass thin film on a Ti substrate to supply Na, the efficiency increased up to 5.59%. In the Na-doped CZTSe absorber layer grown on the Ti substrate, the back crowding of Zn was eliminated and the upper part of the absorption layer was converted to a Zn-rich environment, which prevented the formation of CuZn antisite defects. [Display omitted] •Cu2ZnSnSe4 solar cells on a flexible Ti foil using a two step process.•By supplying Na using soda-lime thin film, the efficiency of 5.59% was obtained.•Na has a great influence on the local distribution of Cu and Zn and hole concentration.•Depending on the presence of Na, the Cu diffusion and the MoSe2 thickness varied.