Our study focuses on the optimization of front contact design by exploring a novel bilayer configuration that employs transparent conductive oxides (TCOs) to enhance the efficiency of thin-film silicon solar cells. The TCOs investigated include sputtered hydrogenated indium oxide (IOH), cerium-doped indium oxide (ICO), cerium and hydrogen co-doped indium oxide (ICOH), and intrinsic zinc oxide (i-ZnO). We highlight the suitability of these TCOs in a bilayer design, first analyzing their opto-electrical properties as monolayers and subsequently in bilayer configurations. The IOH/i-ZnO bilayer architecture, in particular, demonstrates promising opto-electrical properties on both flat glass and micro-textured glass substrates. IOH/i-ZnO on flat glass substrate demonstrates remarkable mobility (143.44 cm²/Vs) and a carrier concentration in the order of 10¹⁹cm^-3. The mean of reflectance (R) trends consistently exceeds 80%, while the mean of transmittance (T) trends falls below 20% beyond 500 nm. The interference effects within the bilayers are minimized for designs on micro-textured glass, preserving values within a desirable range. These findings represent an innovative approach to front contact design for thin-film silicon solar cells, emphasizing the potential of bilayer configurations to advance solar cell technology.

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Transparent conductive oxides (TCOs) are used as front electrode of thin film silicon (TF-Si) solar cells to increase power conversion efficiency. Metal oxides doped with different materials can be deployed as TCO. The preferred TCO is usually selected using a trade-off between transparency and conductivity. This work proposes a bi-layer front contact to address the limitation of this trade-off. IOH and i-ZnO are chosen as the best candidates for such architecture due to their good opto-electrical properties. A thin layer of IOH ensures good lateral conductivity and high transparency in the visible part of the solar spectrum. An additional i-ZnO layer provides minimized parasitic absorption losses along with low transverse resistivity. The best opto-electrical properties are achieved when deposition temperature and power density are set at 25°C and 1.5 W/cm², 200°C and 2 W/cm² for IOH and i-ZnO respectively.

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An alloy based on the group IV elements germanium and tin has the potential of yielding an earth-abundant low bandgap energy semiconductor material with applications in the fields of micro-electronics, optics, photonics and photovoltaics. In this work, the first steps towards the plasma enhanced chemical vapour deposition (PECVD) processing of a chemically stable, low bandgap energy and intrinsic GeSn:H alloy are presented. Using a tetramethyltin (TMT) precursor, over 70 PECVD processed films are presented. It was observed that the opto-electrical film properties are a result of the material phase fraction, void fraction, hydrogenation and the level of tin and carbon integration. In particular, managing the carbon integration from the TMT precursor into the material is crucial for obtaining low-bandgap and chemically stable materials. The collective findings from this work will aid in successfully identifying PECVD processing pathways for GeSn:H.@en

In this paper the opto-electrical nature of hydrogenated group IV alloys with optical bandgap energies ranging from 1.0 eV up to 2.3 eV are studied. The fundamental physical principles that determine the relation between the bandgap and the structural characteristics such as material density, elemental composition, void fraction and crystalline phase fraction are revealed. Next, the fundamental physical principles that determine the relation between the bandgap and electrical properties such as the dark conductivity, activation energy, and photoresponse are discussed. The unique wide range of IV valence alloys helps to understand the nature of amorphous (a-) and nanocrystalline (nc-) hydrogenated (:H) germanium films with respect to the intrinsicity, chemical stability, and photoresponse. These insights resulted in the discovery of i) a processing window that results in chemically stable Ge:H films with the lowest reported dark conductivity values down to 4.6·10^-4 (Ω ·cm)^-1 for chemical vapor deposited Ge:H films, and ii) O, C and Sn alloying approaches to improve the photoresponse and chemical stability of the a/nc-Ge:H alloys.

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