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Towards High Solar Cell Efficiency with Low Material Usage: 15% Efficiency with 14 ?μm Polycrystalline Silicon on Glass
摘要： This work showcases a bottom-up approach to creating silicon solar cells using a line-shaped laser. We report efforts to create thicker amorphous silicon passivation and contact layers as well as laser firing for low contact resistance. Collectively, a new in-house record efficiency of 15.1 % was achieved along with a clear pathway to reach 16 % efficiency with optimization of series resistance.
关键词： Foreign substrates,Liquid phase crystallized silicon,Passivation,Silicon Heterojunction Interdigitated back contact,Laser fired contacts
更新于2025-11-14 15:25:21
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A novel silicon heterojunction IBC process flow using partial etching of doped a-Si:H to switch from hole contact to electron contact <i>in situ</i> with efficiencies close to 23%
摘要： We present a novel process sequence to simplify the rear‐side patterning of the silicon heterojunction interdigitated back contact (HJ IBC) cells. In this approach, interdigitated strips of a‐Si:H (i/p+) hole contact and a‐Si:H (i/n+) electron contact are achieved by partially etching a blanket a‐Si:H (i/p+) stack through an SiOx hard mask to remove only the p+ a‐Si:H layer and replace it with an n+ a‐Si:H layer, thereby switching from a hole contact to an electron contact in situ, without having to remove the entire passivation. This eliminates the ex situ wet clean after dry etching and also prevents re‐exposure of the crystalline silicon surface during rear‐side processing. Using a well‐controlled process, high‐quality passivation is maintained throughout the rear‐side process sequence leading to high open‐circuit voltages (VOC). A slightly higher contact resistance at the electron contact leads to a slightly higher fill factor (FF) loss due to series resistance for cells from the partial etch route, but the FF loss due to J02‐type recombination is lower, compared with reference cells. As a result, the best cell from the partial etch route has an efficiency of 22.9% and a VOC of 729 mV, nearly identical to the best reference cell, demonstrating that the developed partial etch process can be successfully implemented to achieve cell performance comparable with reference, but with a simpler, cheaper, and faster process sequence.
关键词： interdigitated back contact (IBC),H2 plasma,amorphous silicon,heterojunction,dry etch,process simplification,NF3/Ar plasma,in situ processing
更新于2025-09-23 15:23:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Room Temperature Processed Transparent Cu-Zn-S Nanocomposites as Hole Transport Materials in CdTe Photovoltaics
摘要： Here, we report room temperature processed Cu-Zn-S ternary thin films fabricated using SILAR method as a back-contact hole transport layer in cadmium telluride (CdTe) solar cells. These Cu-Zn-S films are transparent to visible region with compact grains, and high conductivity. X-ray diffraction (XRD) measurements shows the crystalline nature of the as-deposited Cu-Zn-S films. The Cu-Zn-S nanocomposite as a back contact buffer layer in CdTe devices improves the device performance to 12.7% (average 12.4%) from 10.4% (average 9.8%) compared to a Au only back contact and is comparable to Cu/Au back contact (thermally evaporated). The temperature dependence current voltage characteristics shows the reduced back barrier height compared to Au only and Cu/Au back contact.
关键词： SILAR,Cu-Zn-S,back contact,hole transport layer (HTL),solar cells
更新于2025-09-23 15:21:01
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Sputtered p-type Cu <sub/>x</sub> Zn <sub/>1-x</sub> S back contact to CdTe solar cells
摘要： As thin film cadmium telluride (CdTe) solar cells gain prominence, one particular challenge is optimizing contacts and their interfaces to transfer charge without losses in efficiency. Back contact recombination is still significant and will prevent CdTe solar technology from reaching its full potential in device efficiency, and transparent back contacts have not been developed for bifacial solar technology or multijunction solar cells. To address these challenges, this study investigates sputtered CuxZn1-xS as a p-type semi-transparent back contact material to thin film polycrystalline CdTe solar cells, at Cu concentrations x = 0.30, 0.45 and 0.60. This material is selected for its high hole conductivity (160 to 2,120 S cm-1), wide optical band gap (2.25 to 2.75 eV), and variable ionization potential (approximately 6 to 7 eV) that can be aligned to that of CdTe. We report that without device optimization, CdTe solar cells with these CuxZn1-xS back contacts perform as well as control cells with standard ZnTe:Cu back contacts. We observe no reduction in external quantum efficiency, low contact barrier heights of approximately 0.3 eV, and carrier lifetimes on par with those of baseline CdTe. These cells are relatively stable over one year in air, with VOC and efficiency of the x = 0.30 cell decreasing by only 1% and 3%, respectively. Using SEM and STEM to investigate the CuxZn1-xS?CdTe interface, we demonstrate that the CuxZn1-xS layer segregates into a bilayer of Cu-Te-S and Zn-Cd-S, and thermodynamic reaction calculations support these findings. Despite its bilayer formation, the back contact still functions well. This investigation explains some of the physical mechanisms governing the device stack, inspires future work to understand interfacial chemistry and charge transfer, and elicits optimization to achieve higher efficiency CdTe cells.
关键词： solar cell back contact design,transparent semiconductors,copper zinc sulfide,solar cell interfaces,CdTe photovoltaics
更新于2025-09-23 15:21:01
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Solar Cells || Review on Metallization in Crystalline Silicon Solar Cells
摘要： Solar cell market is led by silicon photovoltaics and holds around 92% of the total market. Silicon solar cell fabrication process involves several critical steps which affects cell efficiency to large extent. This includes surface texturization, diffusion, antireflective coatings, and contact metallization. Among the critical processes, metallization is more significant. By optimizing contact metallization, electrical and optical losses of the solar cells can be reduced or controlled. Conventional and advanced silicon solar cell processes are discussed briefly. Subsequently, different metallization technologies used for front contacts in conventional silicon solar cells such as screen printing and nickel/copper plating are reviewed in detail. Rear metallization is important to improve efficiency in passivated emitter rear contact cells and interdigitated back contact cells. Current models on local Al contact formation in passivated emitter rear contact (PERC) cells are reviewed, and the influence of process parameters on the formation of local Al contacts is discussed. Also, the contact mechanism and the influence of metal contacts in interdigitated back contact (IBC) cells are reviewed briefly. The research highlights on metallization of conventional screen printed solar cells are compared with PERC and IBC cells.
关键词： interdigitated back contact cells,silicon solar cells,passivated emitter rear contact cells,metallization,process flows
更新于2025-09-23 15:19:57
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Lithography-free and dopant-free back-contact silicon heterojunction solar cells with solution-processed TiO2 as the efficient electron selective layer
摘要： Lithography-free interdigitated back-contact silicon heterojunction (IBC-SHJ) solar cells with dopant-free metal oxides (TiO2 and MoOx) as the carriers selective transport layers were investigated. Spin-coating and hot-wire reactive-sublimation deposition together with low cost mask technology were used to fabricate the solar cells. Insertion of a SiOx layer with the thickness of about 2.4 nm between the intrinsic amorphous Si (a-Si:H(i)) passivation layer and the spin-coated TiO2 layer greatly improves the solar cell performance due to the enhanced field-effect passivation of the a-Si:H(i)/SiOx/TiO2 layer stack. Efficiency up to 20.24% was achieved on the lithography-free and dopant-free IBC-SHJ devices with a-Si:H(i)/SiOx/TiO2 layer stack as the electron selective transport layer, a-Si:H(i)/MoOx as the hole selective transport layer, and WOx as the antireflection layer. The novel IBC-SHJ solar cells show significant advantages in simplification of the technology and process compared with the IBC-SHJ devices whose back surface pattering and carrier selective layers relied on photolithography and plasma enhanced chemical vapor deposition (PECVD).
关键词： Heterojunction,Dopant-free,Back-contact,Lithography-free,Passivation
更新于2025-09-23 15:19:57
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Laser firing in silicon heterojunction interdigitated back contact architecture for low contact resistance
摘要： This work reports a laser firing technique applied to completed silicon heterojunction interdigitated back contact solar cells in order to lower contact resistance. Previously, the implementation of a-Si:H(i) at the electron contact of polycrystalline silicon solar cells on glass substrates led to an increase in series resistance. The cell architecture with the current record efficiency of 14.2% (with illumination through glass) utilizes only an a-Si:H(nt) layer (cid:0) 2 of short circuit current density is lost due to electrical shading under the electron contact and 2–2.9 mA cm [1,2]. The goal of implementing an a-Si:H(i) layer and laser firing at this contact is to achieve low contact resistance at fired spots while preserving a-Si:H(i) passivation in unfired regions. After the laser firing, VOC was (cid:0) 2 loss in JSC. In the best retained, while up to 14% absolute increase in FF was obtained with a mere 0.2 mA cm (cid:0) 2 loss in JSC. Two laser sources were used to first performing cell, a 72.1% FF was achieved with a 0.7 mA cm ablate a part of the silver contact metal, and then to laser fire through the Si(n)/a-Si:H(i/nt)/ITO/Ag contact. (cid:0) 2 (355 nm, picosecond pulse duration) and The optimal laser fluence was found to be 1.1–0.5 J cm (cid:0) 2 (532 nm, nanosecond pulse duration), respectively. The upper limit on specific contact resistance 4.4–5.2 J cm in the laser fired spots was calculated to be 38 ? 20 mΩcm2 as a conservative estimate.
关键词： Liquid phase crystallized silicon,Passivation,Interdigitated back contact,Foreign substrates,Laser fired contacts,Silicon heterojunction
更新于2025-09-23 15:19:57
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Comparative study of optimised molybdenum back-contact deposition with different barriers (Ti, ZnO) on stainless steel substrate for flexible solar cell application
摘要： In this study, we optimised the molybdenum (Mo) back-contact layer for solar cell applications on stainless steel substrates using direct-current (dc) sputtering with varying sputtering powers (100 W to 500 W) and pressures (5 mTorr to 20 mTorr). We comparatively analysed the effectiveness of titanium (Ti) layer deposited using e-beam evaporation deposition and zinc oxide (ZnO) layer deposited using radio-frequency (RF) sputtering for barrier application with Mo. Structural characterisation of the optimised Mo films was carried out using XRD studies confirmed the (110) plane corresponding to the body-centred cubic (bcc) structure. Estimated Mo film parameters for films deposited on barrier layers were compared against films deposited on SS substrate without any barriers as these properties influence the prospective diffusion of Fe and Cr into the absorber layer. Surface characterisation of the deposited films was carried out using a scanning electron microscopy (SEM) to study the morphology of films, and energy-dispersive X-ray (EDX) to identify elemental presence to confirm the blockage of the impurities atoms through the film. Secondary ion mass spectroscopy (SIMS) was employed to study the depth profiles of films while atomic force microscopy (AFM) was used to characterise the topographical properties from the sputtered Mo film and analyse the grain properties of the films. A low resistivity value of 0.511 × 10–6 Ω m for Mo films on the reference glass substrate and 0.625 × 10–6 Ω m for the Mo film on ZnO barrier was measured using the four-point probe. We observed a further 40% reduction in impurities using annealed ZnO barrier combined with an optimised Mo layer.
关键词： flexible solar cell,stainless steel substrate,sputtering,barrier layers,molybdenum back-contact
更新于2025-09-23 15:19:57
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Characterization of sputtered MoOx thin films with different oxygen content and their application as back contact in CdTe solar cells
摘要： Transparent MoOx thin films with varied composition were successfully prepared by sputtering and the effects of oxygen contents on the composition stoichiometry, defect states, work functions, electrical and optical properties of MoOx films were systematically studied. These thin films were then utilized in cadmium telluride solar cells to act as back contact buffers. As compared with the CdTe solar cells with Au back contact, deteriorated performance was witnessed in those with MoOx buffers. The deterioration was demonstrated to be caused by the oxidation of CdTe surface, the large valence band offset and the insufficient work function. Finally, by optimizing the back contacts to form a CuCl/MoOx/ITO composite back contact, the efficiency was improved to 11.8%. This work demonstrates feasible approaches to prepare MoOx thin films with varied oxygen concentrations which could be easily applied to many other thin film solar cells and provide important indications in the preparation and optimization of the performance for bifacial devices.
关键词： Back contact,CdTe solar Cells,Molybdenum oxide,Magnetron sputtering
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Novel Foil Interconnects for Back-Contact Silicon Solar Cells
摘要： Large area back-contact solar cells enable module costs almost as low as those of PERCs but with higher efficiency. Traditional tabbing and stringing interconnects are problematic for back-contact cells, however, as placing all the tabs on one side of the wafer causes bowing due to CTE mismatch. Back-contact cells can be effectively encapsulated using Cu conductive back-sheets (CBS) with electrically conductive adhesive (ECA) interconnects but the cost is higher than for ribbon tabbing. In this paper we present a method for replacing the Cu CBS with a cheaper Al version and the ECA with several cheaper and potentially more robust methods for connecting the foil to the cell.
关键词： laser welding,conductive adhesives,reliability,Back-contact modules,aluminum interconnects,conductive back-sheets
更新于2025-09-19 17:13:59