Thermal decomposition of the molecular single-source precursor (PPh 3 ) 2 CuIn(SEt) 4 in the presence of hexanethiol in dioctylphthalate forms colloidal CuInS 2 at 200 °C. The colloidal solution displays size-dependent quantum confinement behavior in the absorption and photoluminescence spectra. The average size of the nanocrystals can be increased from 2 to 4 nm by raising the reaction temperature from 200 °C to 250 °C. The nanoparticles are capped with hexanethiol ligands; these ligands can be exchanged with trioctylphosphine oxide or pyridine. The nature of the surface-capping ligands has a significant effect on the photoluminescence emission intensity. Investigation of the effect of synthesis parameters and postsynthesis treatments on the optical properties of the nanocrystals leads to the conclusion that the room-temperature emission originates in donor-acceptor defects.

Nanometer-sized particles of the chalcopyrite compounds CuInS 2 and CuInSe 2 were synthesized by thermal decomposition of molecular single-source precursors (PPh 3 ) 2 CuIn-(SEt) 4 and (PPh 3 ) 2 CuIn(SePh) 4 , respectively, in the noncoordinating solvent dioctyl phthalate at temperatures between 200 and 300 °C. The nanoparticles range in size from 3 to 30 nm and are aggregated to form roughly spherical clusters of about 500 nm in diameter. X-ray diffraction of the nanoparticle powders shows greatly broadened lines, indicative of very small particle sizes, which is confirmed by TEM. Peaks present in the XRD can be indexed to reference patterns for the respective chalcopyrite compounds. Optical spectroscopy and elemental analysis by energy dispersive spectroscopy support the identification of the nanoparticles as chalcopyrites.

GaP tensile strain compensation (SC) layers were introduced into GaAs solar cells enhanced with a five layer stack of InAs quantum dots (QDs). One sun air mass zero illuminated current-voltage curves show that SC results in improved conversion efficiency and reduced dark current. The strain compensated QD solar cell shows a slight increase in short circuit current compared to a baseline GaAs cell due to sub-GaAs bandgap absorption by the InAs QD. Quantum efficiency and electroluminescence were also measured and provide further insight to the improvements due to SC.

Investigation of single wall carbon nanotube (SWNT)-polymer solar cells has been conducted towards developing alternative lightweight, flexible devices for space power applications. Photovoltaic devices were constructed with regioregular poly(3-octylthiophene)-(P3OT) and purified, >95% w/w, laser-generated SWNTs. The P3OT composites were deposited on ITO-coated polyethylene terapthalate (PET) and I-V characterization was performed under simulated AM0 illumination. Fabricated devices for the 1.0% w/w SWNT-P3OT composites showed a photoresponse with an opencircuit voltage (V oc ) of 0.98 V and a short-circuit current density (I sc ) of 0.12 mA/cm 2 . Optimization of carrier transport within these novel photovoltaic systems is proposed, specifically development of nanostructure-SWNT complexes to enhance exciton dissociation.

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We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots, using the typical organometallic synthesis routes pioneered by Bawendi et al. in the early 1990s. However, unlike previous work in this area, we have also utilized single‐source precursor molecules in the synthesis process. We present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy is also presented. Theoretical estimates on appropriate quantum dot composition, size, and inter‐dot spacing along with potential scenarios for solar cell fabrication is discussed. Copyright © 2002 John Wiley & Sons, Ltd.

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