Master thesis: Development of Transparent Conductive Oxide (TCO) layers for flexible thin film solar cells
Flexible solar cell panels, made on metal or plastic foils, are an attractive alternative to the conventional silicon-based panels with rigid glass or metal substrates. This is due to a number of advantages, such as (i) compatibility with a roll-to-roll manufacturing process which allows for various widths and lengths and reduces the production cost and also payback time, (ii) flexibility and easy handling, (iii) lightweight and easy installation. Typically, the flexible substrates are opaque or poorly transparent materials such as stainless steel or high temperature polymers, tolerable with respect to the standard deposition temperatures of the silicon layers (around 180°C and above). Such substrates require solar cells in so-called substrate configuration with illumination from the film side. Using instead solar cells in a superstrate configuration with illumination through the substrate would have a number of advantages but would apparently require a transparent substrate and a transparent electrical contact.
The objective of the proposed M.Sc. project is the development of transparent conductive oxide (TCO) materials for application in flexible thin film silicon solar cells in superstrate configuration. The plastic substrates to be used are low temperature Polyethylene terephthalate (PET) which is an extremely low cost, lightweight (around seven times lighter than the stainless steel), flexible and high transparent substrate. The specific goal of this project is the development of various TCO layers at low temperature (T≤140°C) processes. The work includes the following: (i) preparation of TCO layers by sputtering methods at varied parameter range (gas flow ratio, pressure, power, temperature, thickness), (ii) electrical and optical characterization of the layers (Hall mobility, carrier concentration, resistivity, transmission and reflection measurements), (iii) evaluation of light trapping schemes (haze and angular resolved scattering measurement) and the trade-off between electrical and optical properties, (iv) characterization of solar cells (current-voltage and quantum efficiency measurements). The M.Sc. project will be embedded in the network project „FlexSol - Entwicklung und Untersuchung der Beschichtung von Folienbändern mit Kontakten, Barrieren und Solarzellen“ funded by the Bundesministerium für Wirtschaft und Energie (BMWi).
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Please send your application documents to
Ms Andrea Mülheims