CuInS2 thin film prepared by molecular-solution printing technology and its photovoltaic properties

• A modulated molecular-solution printing technology is successfully developed.
• The method is simple, efficient, low-cost for commercial production of solar cell.
• The raw materials Cu2S and In2S3 exist in the precursor film.
• Raw materials change to CIS and partly In2S3, and finally to target CIS phase.
• The fabricated CIS absorber has band gap of 1.34 eV.

Developing efficient, low-cost fabrication technology is the basic requirement for large-scale commercial production of thin film solar cell. In present work, a non-vacuum molecular-solution printing technology was studied for the fabrication of CuInS2 (CIS) thin film solar cell for the first time. Raw materials Cu2S and In2S3 were dissolved by hydrazine to prepare molecular-solution. ɑ-Terpineol and ethyl-cellulose were added into the solution to increase the viscosity of the solution for printing. The printed CIS films were annealed and characterized. It is found that the precursor film includes raw materials Cu2S and In2S3. As the annealing process going, they change to CIS and In2S3, and finally to CIS which turns out apparent photovoltaic characteristic. Experiment results demonstrate the molecular-solution printing technology is simple, high-speed, large scalable and low-cost, which could contribute to the low-cost solar-to-electricity generation.

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