Chemical bath deposition route for the synthesis of ultra-thin CuIn(S,Se)2 based solar cells.

CuIn(S,Se)2 (CISSe) photovoltaic grade thin films are usually grown by expensive vacuum based methods or chemical routes that require highly toxic precursors. In this work, we present the synthesis of CISSe absorbers by a simple chemical bath deposition (CBD) route. In the first step, In2S3/Cu2 − xS stack was deposited as a precursor by CBD on Mo-coated soda lime glass substrates, using respectively thioacetamide and N,N′ dimethylthiourea as S source. Then the CISSe thin films were synthesized by the precursor's selenization at 450 °C. The obtained films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The tetragonal chalcopyrite structure of CISSe was identified by XRD and Raman, confirming that the major part of S was replaced by Se. SEM images show a compact and homogeneous film and by cross-section the thickness was estimated to be around 700 nm. Solar cells prepared with these absorbers exhibit an open circuit voltage of 369 mV, a short circuit current density of 13.7 mA/cm2 , a fill factor of 45% and an efficiency of 2.3%

Impact of Cu-Au type domains in high current density CuInS2 solar cells

In this work, a series of stain steel 15×15 cm2 CuInS2 solar cells with efficiencies close to the record one for this kind of devices, are analyzed. Through a careful and comprehensive study of the structural and electronic properties of the CuInS2 layer, we show that in a general fashion the strain originated by the thermal annealing affects the energy band splitting and reduces the short circuit current. Then, through an innovative combination of photoreflectance and Raman scattering analysis, we demonstrate that the presence of CuAu domains in the bulk layer of a CuInS2 is directly related with this strain reduction contributing to the improvement of short circuit current. We propose that the presence Cu-Au phase domains reduce the strain within the CuInS2 layer, and improve the quality of the CIS chalcopyrite crystals, leading to reduced carrier recombination while increasing carriers mobility. As a consequence we conclude that the presence of said domains improves the short circuit current in the studied devicesPostprint (published version

Impact of Cu-Au type domains in high current density CuInS2 solar cells

In this work, a series of stain steel 15×15 cm2 CuInS2 solar cells with efficiencies close to the record one for this kind of devices, are analyzed. Through a careful and comprehensive study of the structural and electronic properties of the CuInS2 layer, we show that in a general fashion the strain originated by the thermal annealing affects the energy band splitting and reduces the short circuit current. Then, through an innovative combination of photoreflectance and Raman scattering analysis, we demonstrate that the presence of CuAu domains in the bulk layer of a CuInS2 is directly related with this strain reduction contributing to the improvement of short circuit current. We propose that the presence Cu-Au phase domains reduce the strain within the CuInS2 layer, and improve the quality of the CIS chalcopyrite crystals, leading to reduced carrier recombination while increasing carriers mobility. As a consequence we conclude that the presence of said domains improves the short circuit current in the studied device

Combined Raman scattering photoluminescence analysis of Cu In,Ga Se2 electrodeposited layers

This work reports the optical non destructive assessment of the relative Ga content in Cu In,Ga Se2 absorbers synthesized from electrodeposited precursors using combined photoluminescence PL and Raman scattering. Comparison of the PL measurements with the Auger Spectroscopy characterization of the layers has allowed performing a calibration of the dependence of the PL peak energy on the absorber composition. This opens the possibility for the nondestructive chemical assessment of the absorbers synthesized with these low cost processes. Extension of these measurements using a confocal microscope demonstrates their viability for the nondestructive quantitative chemical profiling of the layers. Correlation of these data with Raman spectra measured with the same experimental setup allows deepening in the interpretation of the spectra, giving additional information related to the microcrystalline quality of the layers and the presence of secondary phase