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N-type polycrystalline silicon (poly-Si) thin films are successfully prepared on glass substrates at room temperature by direct current (DC) magnetron sputtering with different DC substrate biases. The effects of different substrate biases on the crystallization, deposition rates, and electrical properties of Si thin films are presented in this work. In this work, we describe a direct method of preparing poly-Si thin films on glass substrates at room temperature, which is considered to be useful for applications in flexible electronics. A significant crystalline fraction value of 85% of the as-deposited Si thin films is obtained at a substrate bias of À50 V. In this work, the high activation rates of impurities at a substrate bias of À50 V result in poly-Si thin films on glass substrates with a resistivity of 1:5 Â 10 À3 cm.

In this work Cu2ZnSnS4 (CZTS) suitable for the absorption layer in solar cells was successfully prepared by sol-gel spin-coated deposition. CZTS precursors were prepared by using solutions of copper (II) chloride, zinc (II) chloride, tin (IV) chloride, and thiourea. The CZTS with texture surface structures, resulting from 3 times of stacks through the cycles of spin-coated and synthesized (at 320 °C) processes, is found to be merged well together, and the thickness of the CZTS reaches ~ 3 μm. The kesterite crystallinity of the CZTS designated from the x-ray diffraction of (112), (200), (312), and (322) planes of CZTS were obtained. The optical-energy gap of the CZTS is about 1.5 eV. The average optical-absorption coefficient of the CZTS is ~ 2.4 x 104 cm-1, and the high absorption band of the CZTS covers most of the solar irradiation spectrum. This makes the CZTS the most potential material for solar cells. The chemical composition Cu:Zn:Sn:S = 30:14:16:40 of the CZTS is obtained at a synthesized temperature of 320 °C.