5:00 PM - ES20.07.29
Highly Efficient Earth-Abundant CZTSSe Solar Cell by Introducing p+-CTSSe Point Contacts
Chih-Yang Huang1,2,3,Cheng-Ying Chen1,2,3,Yu-Chen Chen1,2,Jih-Shang Hwang4,Kuei-Hsien Chen1,2,Li-Chyong Chen1,2,3
National Taiwan University1,Institute of Atomic and Molecular Science, Academia Sinica, Taipei 106, Taiwan2,Center of Atomic Initiative for New Materials, National Taiwan University3,Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan4
Recently, Cu2ZnSn(S,Se)4 (CZTSSe) solar cell has attracted many attentions due to several advantages of CZTS(e) such as earth-abundant, cheap, nontoxic, high absorption coefficient (~10-4 cm-1) and tunable bandgap (1~1.5eV). [1-4] So far, the highest efficiency of CZTS(e) solar cell is 12.6% achieved by IBM team but its power conversion efficiency (PCE) still cannot compete with the commercial thin-film solar cells, e.g., CIGS and CdTe. There are numerous issues need to be solved to enhance the PCE (e.g., back contact losses, interfacial losses, deep defects). Especially, back contact losses cause degradation of CZTS(e) solar cell due to interface defects between CZTS(e) and MoS(e)2 produced by sulfo-selenized Mo-coated soda lime glasses (SLG).
In this work, the PCE of CZTSSe solar cells were greatly improved by a simple but effective method, wherein a CdS nano-layer was deposited between the Mo substrate and the metallic precursors prior to CZTSSe sulfo-selenization, producing p+-CTS(e) and ZnS(e), which helps reduce interface recombination, on the bottom of the CZTSSe absorber layer. The mainly improvement results from increasing fill factor (FF) and short circuit current due to less recombination at back interfaces. Moreover, a 9.61% PCE (~10.6% in the cell effective area) CZTSSe cell with improved FF from 44% to 64% has been attained.
The morphology, elemental composition, and distribution of the absorber layers are being examined by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), Transmission electron microscope (TEM), and Raman spectroscopy.
 V. Tunuguntla, W.C. Chen, P.H. Shih, I. Shown, Y.R. Lin, C.H. Lee, J.S. Hwang, L.C. Chen and K.H. Chen, J. Mater. Chem. A, 2015,3, 15324-15330
 Y.R. Lin, V. Tunuguntla, S.Y. Wei, W.C. Chen, D. Wong, C.H. Lai, L.K. Liu, L.C. Chen and K.H. Chen, Nano Energy, 2015, 16, 438
 W.C. Chen, C.Y. Chen, V. Tunuguntla, S.H. Lu, C. Su, C.H. Lee, K.H. Chen and L.C. Chen, Nano Energy, 2016, 30, 762-770
 C.Y. Chen, B. S. Aprillia, W.C. Chen, Y.C. Teng, C.Y. Chiu, R.S. Chen, J.S. Hwang, K.H. Chen, and L. C. Chen, Nano Energy, 2018, 51, 597-603