This study investigates the transparent conductive oxides (TCOs) as front contact for thin-film solar cell applications by developing a bilayer design that decouples the optical and electrical functionalities. The bilayer front contact structure combines hydrogenated indium oxide (IOH) and non-intentionally doped zinc oxide (ZnO) materials. This design achieves enhanced optoelectrical properties with a mobility of 120 cm²/Vs and a carrier density of 1.97·10¹⁹ cm^-3. Notably, the bilayer outperforms the expected average of its constituent layers in both transparency and conductivity, reflecting the benefits of optimized layer architecture. When integrated as the front electrode in a hydrogenated nanocrystalline silicon (nc-Si:H) solar cell, the IOH/ZnO bilayer yields a fill factor of 64.56 % and a power conversion efficiency of 7.85 %. When using an ITO front contact, the nc-Si:H solar cell reveals a fill factor of 56.27 % and an efficiency of 6.80 %. By successfully decoupling optical and electrical properties, the optimized IOH/ZnO bilayer offers a significant advancement over single-layer TCO configurations, presenting an innovative pathway for enhanced performance in thin-film solar cell technology.

Accurate prediction of optical performance in solar cells with multiscale-textured interfaces is essential for optimizing light management in next-generation photovoltaics. For the first time, a systematic validation of two complementary modeling approaches is carried out on experimentally fabricated thin-film silicon (TF Si) solar cells: rigorous coupled-wave analysis (RCWA), offering a full electromagnetic solution but constrained by boundary conditions, and a ray optics model, operating in the refractive regime. The study involves two device architectures: an a-Si:H single-junction cell on commercial Asahi VU-type glass with random nanotextures, and an nc-Si:H single-junction cell on novel micro-periodic honeycomb-textured glass developed in-house. Simulated and measured external quantum efficiency (EQE) and total front reflection losses (1-R) are benchmarked using the root mean squared error (RMSE). The ray model shows deviations of only 2%–6%, comparable to RCWA, while reducing computation time from 1 week to less than 30 min. Applied to an a-Si:H/nc-Si:H tandem device on honeycomb-textured glass, ray optics reproduced the optical response with spectral deviations below 6% and photocurrent mismatch under 0.2 mA/cm2. These findings uniquely establish ray optics, when combined with accurate optical constants and realistic interface morphologies, as a reliable and computationally efficient predictive tool broadly transferable to thin-film technologies, including perovskites.

This study investigates the influence of reactive sputtering gas composition, specifically the oxygen-to-argon (O2/Ar) and hydrogen-to-argon (H2/Ar) ratios, on the optoelectrical and structural properties of fluorine-doped tin oxide (FTO) and undoped tin dioxide (SnO2) thin films deposited at room temperature (RT). Through systematic variation of O2 and H2 content in the sputtering atmosphere, gas-phase composition is correlated with key performance metrics, including optical transmittance, sheet resistance, carrier density, and mobility, both before and after postdeposition annealing (PDA) at 400 °C in a nitrogen atmosphere. An optimal O2/Ar ratio of 0.3–0.4% achieves the best optoelectrical trade-off in FTO, yielding a minimum sheet resistance (468 Ω/sq) and high mobility (13.7 cm2/(V s)). In SnO2 films, increasing oxygen improves optical transparency but reduces conductivity, while hydrogen incorporation at fixed 1% O2/Ar enhances transparency and lowers sheet resistance in the as deposited state. These effects are attributed to defect passivation rather than changes in oxidation state, as supported by X-ray photoelectron spectroscopy results. Ambipolar conduction observed in the as deposited films transitions to stable n-type behavior after PDA, highlighting the role of thermal treatment. Although RT sputtered SnO2-based films do not yet match the performance of high-temperature grown benchmarks, these findings demonstrate that careful tuning of the sputtering gas composition enables scalable, thermally compatible, and cost-effective fabrication of transparent conducting electrodes and transport layers in photovoltaic applications.

Techniques to facilitate excellent optical yield are required to manufacture high-performing solar cells. In thin-film solar cells, light scattering with the help of textured interfaces increases the absorption path length of photons and reduces the reflection of the photovoltaic active layer. These textures should also facilitate the growth of crack-free thin-film layers, ensuring high efficiency in multijunction devices. This work explores three texturing methods for glass that have the potential to be integrated into solar cells in a superstrate configuration. A detailed study of sacrificial texturing on glass using i-ZnO ((Formula presented.)) and indium-doped tin oxide ((Formula presented.)) is presented. The optical interaction of these textures is correlated to their root-mean-square (RMS) roughness ((Formula presented.)). It is demonstrated that high optical scattering can be achieved for both (Formula presented.) and (Formula presented.) but at different (Formula presented.) regimes. A novel texture with superimposed morphology, named superimposed sacrificial texturing ((Formula presented.)), is created by combining (Formula presented.) and (Formula presented.) through sequential wet etching. The (Formula presented.) exhibits exceptional transmission and light scattering properties. Nanocrystalline silicon (nc-Si:H) single-junction solar cells were fabricated in a superstrate configuration to investigate the impact of these textures on indirect bandgap thin-film solar cells. The efficiency of solar cells on (Formula presented.) is nearly 0.57% and 1.52% (absolute) more than (Formula presented.) and (Formula presented.) solar cells, respectively. By superimposing two textures, solar cells can combine the advantages of enhanced optical performance with high-quality nc-Si:H material growth.

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.

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.

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.

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.

We extended the capabilities of our GenPro4 solar cell optical model, making it an even more powerful tool for nanotexture optimization. We show its application to thin-film CIGS, silicon, and perovskite/silicon tandem solar cells.