Ternary Chalcogenide‐Based Photoelectrochemical Cells: IV . Further Characterization of the Polysulfide Systems

Abstract

The photoelectrochemistry of n-CuInS2 and CuInSe2 in polysulfide electrolyte is studied with particular emphasis on the pretreatments of the electrodes and on their output stability. The use of Cd doping, (photoelectro)chemical etching, and mild air oxidation all were found to improve electrode performance. The effect of air oxidation was reproducible only for the diselenide, where it improved the fill factor and, because of a negative shift of the flatband potential, the open-circuit voltage. Optimized cells showed, at elevated temperatures, conversion efficiencies around 5 and 7.5% for the sulfide and selenide, respectively. The positive temperature dependence of the photo-I-V characteristics at both low and high illumination intensities, the existence of optimal polysulfide solution compositions, the linear dependence of the photocurrent on the light intensity, and the effects of temperature, solution composition, and initial current density on the photocurrent decrease during the first minute of operation of the cells, are ascribed to limitations of the charge-transfer process across the solid/liquid interface. Thermally activated rates of ad-and desorption of sulfur containing solution species on the semiconductor surface and/or the presence of adsorption-induced electronic states in the bandgap are postulated as causes for this behavior. Notwithstanding these limitations the cells are resistant to photocorrosion, after the initial decrease is arrested, in contrast to what is known for similar Cd-chalcogenide-based systems. We suggest that this stability, which persists under load and at high light intensities, is due to the strength and character of the bonds in CuIn-dichalcogenides, or to the presence of a top layer of indium oxide in which recombination will take place, or to both.

General synthesis of I–III–VI2 ternary semiconductor nanocrystals

“…11,12 Chalcopyrite semiconductor CuInS 2 has also attracted much attention as an ideal candidate for use in thin-film solar cells owing to its high absorption coefficient and optimal band gap energy of 1.45 eV, which is well matched to the solar spectrum. 13,14 AgInSe 2 , a semiconductor with a band gap of 1.19 eV, is one of the most useful materials for NIR application as well as for the preparation of Schottky diodes and solar cells. 15,16 There have been many methods for the synthesis of I-III-VI 2 ternary compounds, such as molecular beam deposition, chemical vapor deposition, hydrothermal or solvothermal technique, single-source precursor route, etc.…”

Toward highly efficient CdS/CdSe quantum dot-sensitized solar cells incorporating a fullerene hybrid-nanostructure counter electrode on transparent conductive substrates

“…[15][16][17] Alternatively, various carbon materials with good corrosion inertness toward polysulde redox couple and larger specic surface area with porous structure, have been applied in QDSCs. [18][19][20][21] Meng et al introduced activated carbon into QDSC as counter electrode and demonstrated that activated carbon exhibits better catalytic property against Pt toward polysulde electrolyte. 22 Fan et al explored CdSe QDSC based on hierarchical nanostructured spherical carbon electrode with hollow core/mesoporous shell, showing 3.90% efficiency.…”

Photoelectrochemical characterization of CuGaSe/sub 2/ and Cu(Ga,In)Se/sub 2/ films and defect chemical implications for solar cell performance

“…Optical Bandg ap - by ilnddng in@urity bands (10). Rinccpl has to the quantum yield for photmurrent gemration as given in Table I.…”