Physico-Chemical nanomaterials science

Development of low-cost methods post-synthetic treatment for fabrication effective solar cells based on Cu2ZnSnS4
Babichuk I.S.1,2, Semenenko M.O.2, Golovynskyi S.1,2, Caballero R.3, Datsenko O.I.4, Babichuk I.V.5, Baikui Li1, Qu Junle1
1 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, P.R. China.
E-mail: ivan@szu.edu.cn; babichuk@isp.kiev.ua
2 Institute of Semiconductor Physics, NAS of Ukraine, 03680, Kyiv, Ukraine.
3 Universidad Autónoma de Madrid, Departamento de Física Aplicada, 28049, Madrid, Spain
4 Department of Physics, Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine.
5 National Center “Minor academy of sciences of Ukraine”, 04119, Kyiv, Ukraine.

Semiconductor Cu2ZnSnS4 (CZTS) is an attractive earth-abundant material for fabrication of solar cells. CZTS is characterized by direct bandgap, high absorption coefficient as well as cost efficiency and nontoxicity of the initial components, which are widely spread in the crust and sustainable in the manufacturing processes.
We propose a method to improve electro-optical and structural parameters of light absorbing kesterite materials. It relies on the application of weak power hydrogen plasma discharges using electromagnetic field of radio frequency (13.56 MHz), which improves homogeneity of the films. For our aims, we utilize three kinds of CZTS samples with tetragonal structure. The control and post-treated samples are thoroughly characterized by microscopy, crystallographic, optical and electrical methods.
The analysis has shown that the plasma treatment results to an improvement in the surface layer (the position of main kesterite band 336 cm-1 shifted to the high-frequency region by 2 cm-1), which is stable during long period. Such a processing can be performed inside a vacuum chamber during the post-processing stage.
We conclude therefore that proposed treatment might be applied for the creation of light absorbers with reduced strains and be suitable for the production of multi-layer thin film solar cells.