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In silicon thin-film solar cells the interface between the i- and p-layer is the most critical. In the case of back diffusion of photogenerated minority carriers to the i/p-interface, recombination occurs mainly on the defect states at the interface. To suppress this effect and to reduce recombination losses, hydrogen plasma treatment (HPT) is usually applied. As an alternative to using state of the art HPT we apply an argon plasma treatment (APT) before the p-layer deposition in n-i-p solar cells. To study the effect of APT, several investigations were applied to compare the results with HPT and no plasma treatment at the interface. Carrier collection losses in resulting solar cells were examined with spectral response measurements with and without bias voltage. To investigate single layers, surface photovoltage and X-ray photoelectron spectroscopy (XPS) measurements were conducted. The results with APT at the i/p-interface show a beneficial contribution to the carrier collection compared with HPT and no plasma treatment. Therefore, it can be concluded that APT reduces the recombination centers at the interface. Further, we demonstrate that carrier collection losses of thin-film solar cells are significantly lower with APT. [ABSTRACT FROM AUTHOR]

Mechanism of the reaction in which CuInSe nanoparticles are formed in synthesis by the microwaveassisted polyol method was studied. The morphology and optical properties of thin layers (films) produced from the synthesized CuInSe nanoparticles and the morphology and photoelectric properties of composite films based on CuInSe and [6,6]phenyl C61 butyric acid methyl ester were examined. It is shown that CuInSe nanoparticles can be used to form a photo-absorbing layer in composite organo-inorganic solar cells. [ABSTRACT FROM AUTHOR]

Recent interests focus on tin mono sulphide as a potential candidate for an absorber layer in heterojunction solar cells. In the present investigation, SnS thin films have been deposited onto different substrates such as glass, ITO and Mo-coated glass substrate by thermal evaporation method. The compositional, microstructural and photoelectrochemical properties of the SnS films were analyzed depending upon the chemical nature of the substrates used. The SnS layers were polycrystalline with Herzbergite orthorhombic structure on all three substrates and had nearly stoichiometric elemental composition with a Sn/S ratio of ~1.01. The films grown on ITO and Mo-coated glass substrates exhibit (040) as preferred orientation whereas the films deposited on glass showed (111) plane as predominant. The layers were densely packed and well adherent to the substrate surface. The Raman spectra showed bands at 64, 163, 189 and 219 cm −1, which corresponds to the single phase (SnS) composition of films. p-type conductivity of all the deposited films were determined by the photoresponse studies. The highest photoresponse for the films on the ITO substrate indicates their appropriateness for the solar cell application. [ABSTRACT FROM AUTHOR]

Thin films of Cu-In-Se (CISe) photoabsorber with an overall composition of CuInSe were deposited onto glass/indium tin oxide (ITO) substrates from a polycrystalline bulk CuInSe source using the high-vacuum evaporation technique. Thermal conditions for the substrates during the evaporation process and the subsequent annealing in vacuum were selected to prepare polycrystalline n-CuInSe photoabsorber layers for use in hybrid photovoltaic structures based on an inorganic photoabsorber and conductive polymer functional layers. The CISe layers were deposited at a substrate temperature of 200°C and were annealed at temperatures from 300°C to 500°C in vacuum. Part of the as-deposited CISe was annealed twice, in argon and in vacuum at 500°C. These layers exhibited high photosensitivity and photoconductivity when illuminated with white light at an intensity of 100 mW/cm. The results showed that the chalcopyrite structure of the prepared CISe photoabsorber films adhered well to the glass/ITO substrate. The average value of charge carrier concentration and the profile of charge carrier concentration in the annealed CISe photoabsorber layer were calculated using impedance spectroscopy. [ABSTRACT FROM AUTHOR]

The effect of the deposition of layers "polymer-dye" with different types of conductivity on the surface photovoltage (V) of CuInS2 (CIS) has been studied. The influence of composite layers depends on the molecular structure of a polymer, the type of conductivity and photosensitivity of a dye. The photovoltage growth mainly in the region of strong absorption of a dye was observed after the deposition of the composite consisted of the p-type polymethine dye and the carbazole I-contained polymer on the CIS surface. The spectral dependence of this composite in the low-absorption region is only weakly changed. On the contrary, the deposition of the composite consisted of the perylene n-type dye in polymer on CIS leads to a decrease of V, especially in the dye absorption region. A decrease of the short-wavelength slope is caused by the presence of surface recombination centers in CIS films. The above-mentioned results can be explained by the presence of a few concurrent processes, the efficiency of which strongly depends on the used polymer and the type of conductivity of a dye. [ABSTRACT FROM AUTHOR]

This study is devoted to the properties of the CuInS2 (CIS) surface and the effect of thin organic layers on them. The CIS layers under study feature photosensitivity in the range of 1.5–3 eV. A quadratic approximation of the long-wavelength edge of a spectral dependence of the photovoltage yields the band gap E g =1.46±0.02 eV. It is shown that the major contribution to the formation of the barrier near the CIS free surface is made by acceptor levels arranged higher than the CIS valence band top by ∼0.1 and ∼0.2 eV. As a polymeric layer is deposited onto the CIS free surface, the potential barrier height slightly decreases, while the carrier transport efficiency simultaneously increases. As an organic p-type semiconductor is deposited onto the CIS free surface, trapping centers are partially neutralized, and the carrier recombination rate on the CIS film surface decreases. [ABSTRACT FROM AUTHOR]

We report on the observation of efficient terahertz radiation from the surface of CuInSe2 excited by femtosecond laser pulses. Terahertz radiation emitted by polycrystalline CuInSe2 layers manufactured by using electrodeposition technology was as powerful as the signals radiated by single-crystalline semiconductor surfaces. It has been found that terahertz radiation efficiency is critically dependent on the stoichiometry of the CuInSe2 layers. The results of a double-pulse excitation experiment have indicated that terahertz radiation from the photoexcited surfaces of CuInSe2 samples was caused by the presence of a built-in electrical field at those surfaces. [ABSTRACT FROM AUTHOR]

Terahertz pulse generation at the surfaces of chalcopyrite I-III-VI2 compounds prepared by several different technologies is presented and attempts to increase the emitted THz power by applying a reverse electrical bias to the surface structure are described. Three types of differently grown chalcopyrite samples were investigated. The largest terahertz pulse amplitudes were obtained when single crystalline CISe was used. Relatively strong THz emission was also observed from the surfaces of polycrystalline CISe and CIS layers. A significant enhancement of the amplitude by more than five times was achieved by applying an external bias to the surface of the CIS layer. [ABSTRACT FROM AUTHOR]

The precursor stacked films of consistent binary chalcogenides (ZnSe, SnSe, CuSe) were deposited onto molybdenum covered soda-lime glass substrates by vacuum evaporation. Thermal treatments in SnSe2 or elemental selenium containing atmospheres were used for copper-zinc-tin-sulphide (CZTSe) formation. XPS investigations confirm the formation of CZTSe films homogeneous in bulk in both selenization atmospheres. At the same time, surface area composition of films selenized in Se and SnSe2 differed and the surface layer of CTZSe films selenized in SnSe2 atmosphere was tin-rich, containing separate phases of Se and SnSe2. The etching of CZTSe films with 1% Br2-MeOH (bromine in methanol) at the rate of 75 nm/s removed mainly metals from the surface films and left precipitates of Se on the surface. Solar cell structures with the efficiency of about 3% were developed using selenized and etched films. [ABSTRACT FROM AUTHOR]