LOW-COST SCHOTTKY-BARRIER SOLAR-CELLS FABRICATED ON CDSE AND SB2S3 FILMS CHEMICALLY DEPOSITED WITH SILICOTUNGSTIC ACID

A novel method for fabricating high efficiency metal (Pt, Au, and Ni)/(CdSe or Sb2S3) Schottky barrier solar cells is reported. The method is based on the fabrication of n-CdSe or Sb2S3 thin films chemically deposited with and without silicotungstic acid (STA). The performances of the Schottky junctions fabricated with the films deposited with STA, CdSe(STA), or Sb2S3(STA), are significantly higher than those deposited without STA. Under AM1 illumination, the photovoltaic properties of the improved Pt/CdSe(STA) diode showed V(oc) = 0.72 V, J(sc) = 14.1 mA/cm2, FF congruent-to 0.70, and efficiency eta congruent-to 7.2%. Analogous results are obtained on Pt/n-Sb2S3(STA), where the photovoltaic response of the improved diode showed V(oc) = 0.63 V, J(sc) = 11.3 mA/cm2, FF congruent-to 0.63, and eta congruent-to 5.5%. The ideality factor (n) and saturation current density (J0) were also significantly improved. C-V measurements at 1 MHz showed that the barrier height (phi(b)) of the fabricated diodes are 0.62 and 0.59 eV for Pt/CdSe and Pt-Sb2S3 junctions, respectively, and 0.81 and 0.80 eV for Pt/CdSe(STA) and Pt-Sb2S3(STA) junctions, respectively. It is also observed that the phi(b) values are independent of the metal work functions (W). This is attributed to the Fermi level pinning of CdSe or Sb2S3 films deposited with and without STA.