Premium
Fill Factor Losses in Cu 2 ZnSn(S x Se 1− x ) 4 Solar Cells: Insights from Physical and Electrical Characterization of Devices and Exfoliated Films
Author(s) -
Tai Kong Fai,
Gunawan Oki,
Kuwahara Masaru,
Chen Shi,
Mhaisalkar Subodh Gautam,
Huan Cheng Hon Alfred,
Mitzi David B.
Publication year - 2016
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201501609
Subject(s) - materials science , kesterite , band gap , equivalent series resistance , raman spectroscopy , solar cell , x ray photoelectron spectroscopy , electrical resistivity and conductivity , analytical chemistry (journal) , optoelectronics , czts , optics , voltage , nuclear magnetic resonance , electrical engineering , chemistry , physics , chromatography , engineering
Besides the open circuit voltage ( V OC ) deficit, fill factor (FF) is the second most significant parameter deficit for earth‐abundant kesterite solar cell technology. Here, various pathways for FF loss are discussed, with focus on the series resistance issue and its various contributing factors. Electrical and physical characterizations of the full range of bandgap ( E g = 1.0–1.5 eV) Cu 2 ZnSn(S x Se 1− x ) 4 (CZTSSe) devices, as well as bare and exfoliated films with various S/(S + Se) ratios, are performed. High intensity Suns‐ V OC measurement indicates a nonohmic junction developing in high bandgap CZTSSe. Grazing incidence X‐ray diffraction, Raman mapping, field emission scanning electron microscopy, and X‐ray photoelectron spectroscopy indicate the formation of Sn(S,Se) 2 , Mo(S,Se) 2 , and Zn(S,Se) at the high bandgap CZTSSe/Mo interface, contributing to the increased series resistance ( R S ) and nonohmic back contact characteristics. This study offers some clues as to why the record‐CZTSSe solar cells occur within a bandgap range centered around 1.15 eV and offers some direction for further optimization.