Celdas solares con nanopilares de ZnO embebidos en CuInS2 como absorbente de la radiación

BERRUET, M; DI IORIO, Y.; PEREYRA, C.J; VAZQUEZ, M.; MAROTTI, R.E.

Congreso; Congreso Internacional de Metalurgia y Materiales 16° SAM-CONAMET; 2016

Solid state solar cells for terrestrial use were prepared in superstrate configuration using scalable low-cost techniques. The absorbent layer (CuInS2, CIS) was deposited by spin coating and the transparent layer of nanostructured ZnO by electrodeposition [1,2]. ZnO is a n-type semiconductor with wide band gap. CIS is a p-type semiconductor with a band direct gap of 1.5 eV, ideal to absorb solar radiation. The participation of nanostructured layers ordered as nanopillars, increases the contact area in the junction, improving efficiency in the conversion of energy [3]. The prototypes were prepared on conductive glass substrate (FTO), coated with a thin layer (d-ZnO) and ZnO nanopillars (NP-ZnO), on which CIS is deposited. In order to improve the alignment of the conduction bands between both semiconductors, an ultrathin layer of In2S3 is deposited [2]. The morphology, crystal structure and chemical composition of each material separately were analyzed by SEM/EDS, XRD and Raman spectrometry. Energy gap (Eg) and the type of conduction was assessed through UV-Vis spectra and electrochemical techniques as photocurrent/photopotential. On the FTO/d-ZnO/NP-ZnO/In2S3/CIS/graphite prototype the voltage-current response was evaluated in the dark and under illumination with a solar Simulator for analyzing the photovoltaic response and to estimate the efficiency of the union p-n junction. Prototype with NP-ZnO presented Voc = 0.5 V, Isc = 13 mA/cm2, FF = 0.43 and η = 3%, which resulted in an increment in the efficiency of 600% in comparison with the prototypes without NP-ZnO (Voc = 0.4 V, Isc = 3 mA / cm2, FF = 0.25 and η < 0.5%). Finally, measures for IMVS/IMPS were carried out to estimate mean life time and of transit of the photogenerated electron, so as to explain the previous results from an electrical point of view.