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Performance analysis of c-Si heterojunction solar cell with passivated transition metal oxides carrier-selective contacts
摘要： Transition metal oxides (TMOs) as passivating carrier-selective contact layers are investigated for silicon heterojunction solar cells. MoOx as hole-selective layer and TiOx as an electron-selective layer are explored in detail to design a high-efficiency silicon heterojunction solar cell without any specified surface passivation layer. The thickness and optical transparency of the MoOx hole-selective layer have been evaluated through optical simulation. The impact of TMOs’ work function and their passivation quality has been examined in detail to extract the maximum conversion efficiency from silicon heterojunction solar cells. To increase the optical absorption in c-Si, the micro–nanopillar structure has also been implemented. It has been found that the barrier height at the TMO/silicon heterocontact plays a significant role in the overall performance improvement of the solar cell. The optimized cell design without doping and separate passivating layer can achieve a power conversion efficiency of ~ 22%. Our findings open the potential pathways and opportunities to obtain simplified heterojunction solar cells at lower temperatures and without impurity doping.
关键词： Surface recombination velocity,Carrier-selective contact layers,Transition metal oxides,c-Si heterojunction solar cells
更新于2025-09-23 15:21:01
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Properties of Thermally Evaporated Titanium Dioxide as an Electron-Selective Contact for Silicon Solar Cells
摘要： Recently, titanium oxide has been widely investigated as a carrier-selective contact material for silicon solar cells. Herein, titanium oxide ?lms were fabricated via simple deposition methods involving thermal eVaporation and oxidation. This study focuses on characterizing an /TiO2 electron-selective passivated contact layer with this oxidized method. Subsequently, the SiO2 stack was examined using high-resolution transmission electron microscopy. The phase and chemical composition of the titanium oxide ?lms were analyzed using X-ray di?raction and X-ray photoelectron spectroscopy, respectively. The passivation quality of each layer was con?rmed by measuring the carrier lifetime using quasi-steady-state photoconductance, providing an implied open circuit voltage of 644 mV. UV–vis spectroscopy and UV photoelectron spectroscopy analyses demonstrated the band alignment and carrier selectivity of the TiO2 layers. Band o?sets of ~0.33 and ~2.6 eV relative to the conduction and valence bands, respectively, were con?rmed for titanium oxide and the silicon interface.
关键词： carrier-selective contact cell,band alignment,titanium oxide,electron-selective contact
更新于2025-09-23 15:19:57
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Elucidating Charge Separation in Particulate Photocatalysts Using Nearly-Intrinsic Semiconductors with Small Asymmetric Band Bending
摘要： Photocatalytic water splitting using particulate suspensions is a promising approach for achieving large-scale production of renewable hydrogen fuels. Previous studies have hypothesized that band energy levels of such photocatalysts in water are both flat and symmetrical, and the charge separation in such photocatalysts is driven by random charge carrier diffusion. However, it is not well understood how the observed asymmetry of carrier diffusion is achieved during photocatalysis. To fully understand this charge separation process, we used double-side polished, intrinsic silicon as a model light absorber and manipulated the direction of charge-carrier diffusion using combinations of carrier-selective contacts. Degenerately p-type doped and n-type doped silicon, along with as-grown and annealed TiO2 overlayers grown by atomic layer deposition, were used as carrier selective back and front contacts, respectively. The protective TiO2 layers along with nickel oxide co-catalysts enabled bi-functional, stable silicon photoelectrodes for photoelectrochemical hydrogen evolution and water oxidation in alkaline solution. A device simulation was applied to analyse the experimental results and further gain understandings on the charge separation process in photocatalysts involving semiconductor/liquid junctions. Combined experimental and simulation study indicated that the contacts established asymmetric band bending inside the intrinsic silicon layer and drove the directional charge separation, primarily carrier diffusion. By scaling down the thickness of the silicon layer in the simulation, analogies of charge separation in particulate photocatalysts can be drawn. Based on the understandings from intrinsic silicon, we further revealed that photocatalysts generally do require asymmetric band bending to drive diffusional charge separation, and that a small band edge offset of 0.45 eV between reductive and oxidative catalytic sites can build a sufficient, steady-state photovoltage of over 1.23 V for overall water splitting by using a model SrTiO3 absorber. It provides an insightful guidance for designing efficient and stable particulate photocatalysts especially those using Si and III-V semiconductors with protective layers such as TiO2.
关键词： Carrier-selective contact,Particulate photocatalyst,Charge separation
更新于2025-09-19 17:15:36
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Interfacial engineering to boost photoresponse performance and stability of V2O5/n-Si heterojunction photodetectors
摘要： Transitional metal oxides (TMOs) have demonstrated as a promising alternative to doped layers in high-efficient crystalline silicon heterojunction solar cells. However, the unintentional oxidation causes serious carrier recombination at the interface, which accounts for the low photoelectric conversion efficiency and poor stability. Herein, a self-powered, broad-band, fast-response V2O5/n-Si heterojunction photodetectors (PDs) are fabricated by thermal evaporation of an ultrathin V2O5 thin films on nanoporous pyramid silicon structures. By interfacial engineering with structural optimization and surface methyl passivation, the photodetection performance and stability of V2O5/n-Si PDs can be significantly enhanced. The V2O5/n-Si heterojunction PDs demonstrate a high on/off ratio of 1.4×104, fast-response speed of 9.5 μs, high responsivity of 185 mA·W-1 (@940 nm) and high specific detectivity (1.34×1012 Jones). Based on the energy band alignment analysis, the excellent photoresponse performance is mainly attributed to the efficient carrier separation after surface passivation by methyl group. Additionally, the built-in electric field at the interface also accelerates the charge carrier separation. Our work would contribute to the fabrications of other TMOs-based heterojunctions, and give some enlightening insights into the understanding of carrier transportation in heterojunctions.
关键词： Carrier selective contact,Heterojunction photodetectors,Transition metal oxides,Interface engineering
更新于2025-09-16 10:30:52
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Non-epitaxial carrier selective contacts for III-V solar cells: A review
摘要： In the last few years, carrier selective contacts have emerged as a means to reduce the complexities and losses associated with conventional doped p-n junction solar cells. Still, this topic of research is only at its infancy for III-V solar cells, in comparison to other solar cell materials such as silicon, perovskites, chalcogenides, etc. This could be because high quality III-V solar cell materials can be achieved relatively easily using epitaxial growth techniques such as MOCVD (metal organic chemical vapor deposition) and MBE (molecular-beam epitaxy). However, current epitaxial III-V solar cells are very expensive and cannot compete for the terrestrial market, and therefore, researchers are developing alternative growth methods such as thin-film vapor–liquid–solid (TF-VLS), hydride vapor phase epitaxy (HVPE) and closed space vapor transport (CSVT), which are significantly lower in cost compared to epitaxial III-V solar cells. However, at present, these relatively nascent low cost growth methods, face severe optimization issues when it comes to growth of controlled p-n junction, along with heavily doped window and back surface field layers. In such cases, carrier selective contacts can be hugely beneficial. In this review, we cover some of the most recent research on the use of carrier selective contacts for III-V solar cells. Future prospects, challenges, and new device concepts using carrier selective contacts will also be discussed.
关键词： Passivation,III-V solar cell,Heterojunction,Window layer,Carrier selective contact
更新于2025-09-12 10:27:22