ZnTe Semiconductor-Polymer Gel Composited Electrolyte for Conversion of Solar Energy

Nanostructured cubic p-type ZnTe for dye sensitized solar cells (DSSCs) was synthesized from 1？:？1 molar ratio of Zn？:？Te by 600？W and 900？W microwave plasma for 30？min. In this research, their green emissions were detected at the same wavelengths of 563？nm, the energy gap at 2.24？eV, and three Raman shifts at 205, 410, and 620？cm？1. The nanocomposited electrolyte of quasisolid state ZnO-DSSCs was in correlation with the increase in the , , fill factor (ff), and efficiency (η) by increasing the wt% of ZnTe-GPE (gel polymer electrolyte) to an optimum value and decreased afterwards. The optimal ZnO-DSSC performance was achieved for 0.20？wt% ZnTe-GPE with the highest photoelectronic energy conversion efficiency at 174.7% with respect to that of the GPE without doping of p-type ZnTe. 1. Introduction Since the first report on low-cost dye sensitized solar cells (DSSCs) in 1991 [1], great efforts have been made to improve their performance [2–4]. In spite of their initial success of approximately 11% solar energy conversion efficiency, much effort to improve cell performance has not been made to major breakthrough since then [5]. DSSCs are very attractive and promising alternative for the development of new generation of photovoltaic devices. Recent research has focused on the use of p-type semiconductors and organic hole-transport materials [6–9] that have better mechanical properties and simple fabrication processes. The main difficulty is to form contacts at p-n junctions and the potential of DSSCs using solid state electrolyte is quite low [10]. Thus, both liquid and solid electrolytes are combined to form quasisolid (gel) electrolytes, including the replacement of liquid electrolytes by solid state hole conductors such as p-type semiconductors [11], CuI [12], CuSCN [13, 14], and NiO [15–17] and polymeric electrolytes [18, 19]. In this study, p-type ZnTe as hole collectors in a polymer electrolyte was used to fabricate solid state DSSCs. 2. Experimental Procedures 2.1. p-Type ZnTe To synthesize ZnTe, Zn and Te powders (analytical grade, Fluka) were used without further purification. Four mixtures of 1？:？1 molar ratio Zn？:？Te were mixed by rotation for 1？h at room temperature and loaded into 11？mm I.D. ×？100？mm long silica boats. Each was placed in a horizontal quartz (HQ) tube at a time. The HQ tube was tightly closed and evacuated to ？kPa absolute pressure for removal of air and followed by gradual feeding of argon into this HQ tube. The procedure was repeated three times. Finally, argon in the HQ tube was evacuated to ？kPa constant absolute pressure.