ZnO/CuInSe2 heterojunction prepared by electrodeposition of different substrates

MARIANA BERRUET; MARCELA VAZQUEZ

Cancún, México.

Congreso; XVII Internacional Materials Research Congress y VI NACE Mexican section Corrosion Congress.; 2008

Sociedad Mexicana de Materiales A.C.

The advances in science and technology in the field of renewable energy sources have led to developing a new generation of photovoltaic cells based on nanocrystalline materials. The electrochemical deposition of thin films is a low cost process (using inexpensive equipment and low temperatures), which we have chosen to prepare solar cells in different configurations. The main purpose is to prepare photovoltaic solar cells as efficient as possible in terms of energy conversion. The inorganic heterojunction chosen is based on ZnO (n-type semiconductor) and CuInSe2 (CISe, p-type semiconductor and absorbent of solar radiation), as an extension of previos work done with TiO2 [1]. First, we investigated the deposition of ZnO layers on conductive glass (TCO). Duplex layers consisting of a dense ZnO film and a nanoporous ZnO film on top have been prepared, both previously annealed. We analyzed the route of synthesis and experimental settings to optimize the process. However, these layers partially dissolve when CuInSe2 electrodeposition is attempted at acidic pH values. Currently, we are analysing the incorporation of TiO2 as a buffer layer to electrodeposit then CuInSe2. At the same time we are exploring the feasibility of using complexing agents to increase the pH of the electrolytic bath enabling CISe deposition. A different approach consists of preparing solar cells in reverse order, i.e. starting with the deposition of CuInSe2 on no-transparent metallic substrate (tentatively silver and stainless steel) to finish with a transparent ZnO layer. On each configuration, the composition and morphology, band gap and voltage-current response of each layer is carefully evaluated using scanning electron microscopy, X-ray diffraction and optical absorption spectroscopy. The morphology and the physical and optical properties are in good agreement with those reported in the literature. Also, the efficiency of energy conversion of each proposed configuration is tested for comparative purposes.