A Novel Sol-Gel Route To Pinhole-Free Iron Sulfide Thin Films

The general purpose of the study is to fabricate and improve upon FeS2 thin films which can be used as the photon absorber layer for a heterojunction or homojunction solar cell. This work deals with the preparation of the pyrite by an unconventional sol-gel approach. Thin pyrite films were prepared by sulfurizing the iron oxide films previously deposited through the sol-gel method using iron (III) chloride as a precursor. The structural, morphological, electronic and optical properties of the deposited films were determined using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, Auger electron spectroscopy (AES), UV-Vis absorption spectroscopy, Hall effect and profilometry. The effects of annealing and sulfurization temperatures were studied. The work was also devoted to the research of sodium diffusion from the substrate due to the thermal treatment and its affect on the pyrite films functionality

REACTION PATHWAY INSIGHTS INTO THE SOLVOTHERMAL PREPARATION OF Culn\u3csub\u3e1- x\u3c/sub\u3eGa\u3csub\u3ex\u3c/sub\u3eSe\u3csub\u3e2\u3c/sub\u3e NANOCRYSTALLINE MATERIALS

Reaction pathway investigations of the solvothermal preparation of nanocrystalline Culn1- xGaxSe2 in triethylenetetramine reveal the early formation of a previously unreported Cu2-xSe(S) intermediate. Over 24 hours, this reacts with In and Se species to form CulnSe2(s). If Ga is present, the reaction proceeds over an additional 48 hours to form Culn1-xGaxSe2. Adding ammonium halide salts reduces the CulnSe2 formation time to as little as 30 minutes. It is proposed that in these cases, Cu2-xSe particle growth is limited via a competitive Cu-halide complex formation. The smaller Cu2-xSe particles may react and form CulnSe2 more rapidly. A reaction pathway scheme consistent with experimental results and previous literature reports is proposed

NSC50487

It has recently been established that the ideal bandgap for terrestrial photovoltaics is 1.37 eV and the bandgap for CulnSe2 is only around 1.04 eV. Thus, a larger bandgap is needed. However, neither the substitution of Ga nor of AI has made a high efficiency solar cell absorber with a band gap of 1.37 eV possible. B, an even smaller atom, should require less atomic substitution than either Ga or AI to achieve a wider bandgap. In order to fabricate a thin film of CulnxB1-xSe2 (CIBS), Cu, In and B were deposited from a variety of sputtering targets which were pure Cu, In, and B; a Cu.45ln.55; and a Cu3B2 target. Films were deposited simultaneously and sequentially. After deposition these films were post selenized in another vacuum chamber. Analysis of these films was accomplished using Raman spectroscopy, X-ray diffraction (XRD), and Auger electron spectroscopy (AES). With the difficulties encountered, materials were also deposited in a selenium atmosphere