Effect of post annealing thermal heating on Cu2ZnSnS4 solar cells processed by sputtering technique

In this work, a detailed study of the effect of thermal treatment (hot plate) on a Mo/CZTS/CdS/i-ZnO/ITO solar cell was carried out, which promotes the diffusion of the Cd contained in the window layer of CdS towards the absorber layer of CZTS. The thermal treatment of the Mo/CZTS/CdS/i-ZnO/ITO solar cell was carried out at temperatures ranging from 100 °C to 400 °C and times varying from 3 to 15 min in air atmosphere. The CZTS was grown from deposits of metallic precursors (Cu/Sn/Cu/Zn) by sputtering and annealing at two ramps: 200° C for 45 min with an argon flow of 1 mbar and 550 °C for 5 min at 1 bar in an atmosphere of S + Sn. For the complete solar cells with a hotplate treatment of 280 °C for 6 min an increase of 2.7% to 5.2% of conversion efficiency was observed compared to the solar cell without hotplate treatment. The band gap CZTS decreased from 1.56 to 1.43 eV and Jsc increased from 12.0 mA/cm2 to 15.4 mA/cm2.Peer ReviewedPostprint (author's final draft

CdTe Thin Films: Deposition Techniques and Applications

The II-IV semiconductor compound, CdTe, has suitable electrical and optical properties as photovoltaic and high-energy radiation sensor material. As an absorber material for thin-film-based solar cells, CdTe holds the potentiality to fabricate high-efficiency solar cells by means of low-cost technologies. This chapter presents a comprehensive review on the CdTe thin-film deposition techniques as well as on the several configurations for the solar cell structures that have led the best efficiency conversion. Current CdTe thin-film deposition techniques include sputtering, close spaced vapor transport (CSVT), chemical spray pyrolysis, and electrodeposition. These techniques have easily been adapted to deposit polycrystalline CdTe films on various flexible and rigid substrates. In regard to the device structure configuration, a variety of partner materials (transparent contact, optical window, buffer layer) were tested, and CdTe film thickness was varied to develop opaque and semitransparent devices by some techniques mentioned above. In this chapter, we will discuss about each technique used for CdTe thin-film deposition as well as its advantages and disadvantages