Influence of treatment conditions on chalcopyrite films deposited at atmospheric pressure

Spin‐coating technique was used to deposit precursor layers for chalcopyrite films of the series CuInX2 and Cu(In,Ga)X2 where X = S or Se or (S,Se). The influence of different parameters of the process, such as solution composition, air pre‐treatment and chalcogenation treatment is discussed with respect to film applicability in photovoltaic devices. Layer morphology, stochiometry and crystalline structure varied widely with the different compositions and treatments. Highly oriented CuInSe2 and Cu(In,Ga)Se2 films were obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

Preparation of Cu(In,Ga)Se2 photovoltaic absorbers by an aqueous metal selenite co-precipitation route

In this paper, we report a novel and simple solution-based approach for the fabrication of chalcopyrite Cu(In,Ga)Se2 thin film solar cells. An aqueous co-precipitation method based on metal selenites, M2(SeO3)x (M = Cu, In, Ga) precursors was investigated. The resulting powder, dispersed in a binder to form an ink, was coated on a substrate by doctor blade technique. A soft annealing treatment allowed the reduction of metal selenites into selenides. Further rapid thermal processing (RTP) achieved crystalline chalcopyrite absorber. The obtained layer provides good compositional control and adequate morphology for solar cell applications. The water-based synthesis is a sustainable and simple procedure, and together with doctor blade printing, provides a potential cost-effective advantage over conventional fabrication processes (vacuum-based deposition techniques). The short circuit current (JSC), open circuit voltage (VOC), fill factor (FF), and total area power conversion efficiency (Eff.) of the device are 26 mA/cm2, 450 mV, 62%, and 7.2%, respectively. The effective band gap of 1.12 eV confirmed Ga-incorporation in the CIGS crystal lattice.This work was supported by the Spanish Ministry of Science and Competiveness under INNPACTO Program (IPT-2011-0913- 920000). The authors would like to thanks to Manuel Ocana Jurado ~ (ICMS-CISC) for his help in the XPS measurements. L. Oliveira would like to thank the support of the National Council for Scientific and Technological Development (CNPq) e Brazil

Preparación y estudio de películas delgadas con aplicaciónes fotovoltaicas

La tesis tiene como objetivo investigar métodos de bajo coste para la deposición de películas delgadas con a aplicaciones fotovoltaicas. Particular atención se ha prestado a la aplicabilidad de los materiales obtenidos. La primera parte (en Español) investiga la deposición de películas de dióxido de titanio y la preparación de células de colorante sensibilizadas con electrolitos sólidos. Se han obtenido capas nanocristalinas de anatasa con excelentes propiedades bactericida. La segunda parte investiga métodos de bajo coste para la deposición de capas de calcopiritas CuInS2, CuIn,GaS2 Cu(In,Ga)Se2, Cu(In,Ga)(S,Se)2, Cu2ZnSnS4 y capas búfer sin contenido de cadmio. La mayoría de los métodos empleados han sido novedosos y publicados por primera vez. La eficiencia más alta de conversión fotoellectrica se ha obtenido en la segunda parte con el calcopirita Cu(In,Ga)Se2, llegando al 7.5%

Cu2ZnSnS4 films deposited by a soft-chemistry method

Cu2ZnSnS4 films were deposited on glass substrates by the use of a printing technique. A series of different precursor materials was synthesized by a soft-chemistry route. Suspensions were prepared with or without the addition of a polymeric binder. Precursor films were printed and subjected to different thermal treatments in sulfur containing atmosphere. Parameters such as precursor synthesis conditions, paste composition, binder addition and thermal treatment were studied. X-ray diffraction patterns can be attributed to Cu2ZnSnS4 phase. In some cases secondary phases were detected. The addition of a polymeric binder improved film uniformity but impeded crystalline growth. Optical and materials aspects were discussed in terms of film applicability in photovoltaic devices. © 2008 Elsevier B.V. All rights reserved

Electro deposited In2S3 buffer layers for CuInS2 solar cells

We report the electro deposition of In2S3 buffer layers for CuInS2 solar cells. All materials and deposition conditions were selected taking into account environmental, economic and technological aspects of a potential transfer to large volume industrial production. Different bath compositions and electro deposition parameters were studied. The obtained films exhibited complete substrate coverage, confirmed by SEM and XPS. In/S ratio close to 2/3 was obtained. XPS measurements detected the presence of indium hydroxide, transforming into oxide upon anneal at 200 °C. Maximum photoelectric conversion efficiency of 7.1% was obtained, limited mainly by a low fill factor (51%). Further process optimization is expected to lead to efficiencies comparable to CdS buffers. So far, open-circuit voltages as high as 660 mV were demonstrated. © 2008 Elsevier B.V. All rights reserved

CIGSS films prepared by sol-gel route

Homogeneous layers of amorphous oxides of Cu-In, Cu-In-Ga were deposited by a sol-gel method. Selenization, sulfurization and sequential selenization + sulfurization treatments were performed with elemental S and Se, respectively. Adherent pinhole-free layers were observed by scanning electron microscopy. X-ray diffraction indicated increased gallium incorporation in selenized in comparison with sulfurized films. Band gap values in the range of 1.18-1.63 eV were obtained. © 2008 Elsevier B.V. All rights reserved