Tailoring interfaces in Earth abundant thin film solar cells

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Cu2ZnSn(S,Se)4 (CZTSSe) is a promising photovoltaic material with outstanding optoelectronicproperties and Earth abundant constituents. Among the variety of techniques employed for thepreparation of the absorber layer, solution-based deposition and processing has the potential toprovide low-cost scalable routes to produce photovoltaic devices with high efficiency. Suchresults include the current record efficiency for CZTSSe solar cells at 12.6 % using hydrazinesolutionbased method. On the other hand, nanoparticle inks offer an alternative to avoid usingthe highly toxic and potentially explosive solvent, hydrazine. Deposited from the Cu2ZnSnS4(CZTS) nanoparticle inks, the CZTS precursor thin films annealed in the presence of Se canprovide devices with efficiency up to 9.5%.Northumbria has recently developed a route for fabricating and controlling the electronic andstructural properties of nanoparticle inks. Upon heat treatment a dense and compact film isformed that can be used to fabricate solar cells with efficiencies approaching 7% on rigidsubstrate or a bit less if we use flexible foils. Our attention now focuses on the interfaces withinthe solar cell structure and particularly the pn junction.The key aim of this project is to develop single/multilayer n-type buffer layers usingindium/cadmium/zinc sulphide and zinc/titanium oxide to increase device performance for bothrigid and flexible structures. During the study you will be in control of the complete fabricationprocesses (nanoparticle inks, thin film and solar cells) and will have access to a wide range ofcharacterisation techniques and recently refurbished laboratories. You will also work closely withone of our partners, TescanUK, to observe the layers nano/microstructure and chemicalcomposition while performing in-situ microscopy-stress tests (for example bending of flexiblefilms, heat treatment of the pn junction). This project is suitable for a candidate with stronginterest in semiconductor and device fabrication as well as spectroscopy and microscopy.