Absorber Films of Antimony Chalcogenides via Chemical Deposition for Photovoltaic Application
- PDF / 120,120 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 52 Downloads / 128 Views
L5.37.1
Absorber Films of Antimony Chalcogenides via Chemical Deposition for Photovoltaic Application M. T. S. Nair, Y. Rodríguez-Lazcano, Y. Peña, S. Messina, J. Campos, and P. K. Nair, Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Temixco, Morelos – 62580, México. ABSTRACT Antimony sulfide thin films (300 nm) have been deposited on glass substrates at 1-10oC from chemical bath. When heated these become crystalline and photoconductive with optical band gap (direct) of 1.7 eV. Thin films formed from chemical baths containing SbCl3 and sodium selenosulfate are of mixed phase Sb2O3/Sb2Se3, which when heated in the presence of Se-vapor converts to single phase Sb2Se3 film with optical band gap of 1.1 eV. Such films possess dark conductivity of 10-8 ohm-1cm-1 and show photosensitivity of two orders. Reaction of Sb2S3-CuS in nitrogen at 400oC produces crystalline, photoconductive p-type CuSbS2 with optical band gap (direct) of 1.5 eV. By controlling the deposition and heating condition, (i)Sb2S3-(p)CuSbS2 layer is formed, which is utilized in a photovoltaic structure, (n)CdS:In-(i)Sb2S3-(p)CuSbS2, with a Voc of 345 mV and Jsc 0.18 mA/cm2 under 1 kW m-2 tungsten halogen illumination. In the case of a structure, CdS:ClSb2S3-Cu2-xSe, Voc of 350 mV and Jsc of 0.5 mA/cm2 are observed. INTRODUCTION Antimony chalcogenides are known for their potential as photoconductors, optical storage media and thermoelectric cooling materials. Due to optical band gaps of 1.7-1.8 eV and 1.1 eV, respectively, the sulfides and selenides of antimony with V2VI3 composition are suitable for application as absorber materials in photovoltaic devices. The feasibility of chemically deposited thin films of Sb2Se3 and n-Sb2S3 as active components in photoelectrochemical [1] as well as Schottky barrier and in heterojunction type solar cells has been demonstrated [2]. Thin films of these materials obtained by chemical bath deposition are reported as amorphous in the as-prepared form [3]. Subsequent work on chemically deposited thin films of antimony chalcogenides by our group [4,5] has shown that after annealing in nitrogen at 300 ˚C, the x-ray diffraction (XRD) patterns of the films of antimony sulfide show well defined peaks similar to that of the mineral stibnite, Sb2S3, while those of antimony selenide show in addition to the ones corresponding to Sb2Se3 peaks also due to Sb2O3 as in the mineral senarmontite. The films are photosensitive and exhibit a high resistivity in the dark. We have also shown that a p-type CuSbS2 can be made from the reaction of thin films of intrinsic Sb2S3 with p-type CuS at 400 ˚C [6]. These films show a direct band gap of 1.52 eV and electrical conductivity around 0.03 (Ω cm)-1. The material has prospects for use as an absorber, similar to CuInSe2, where the presence of In(III) in the lattice is believed to inhibit diffusion of Cu(I) ions through the junction to the n-side in a heterojunction solar cell. The present paper deals with results of our continuing investigations on obtaining thin f
Data Loading...
