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Improved Surface Passivation by Wet Texturing, Ozone‐Based Cleaning, and Plasma‐Enhanced Chemical Vapor Deposition Processes for High‐Efficiency Silicon Heterojunction Solar Cells
摘要： This paper reports on the development of wet chemical processes varying the texturing and cleaning of the silicon surfaces, reducing process time and the amount of chemicals to obtain the same cleaning quality. Additionally, two different amorphous silicon (a-Si:H) passivation stacks are discussed in this paper demonstrating an improvement of the open circuit voltage, Voc, by 15 mV. Implementing these wet chemistry improvements combined with optimized process conditions for the passivating a-Si:H layers deposited by plasma enhanced chemical vapor deposition (PECVD), allowed us to obtain high efficiency devices both in small and full-area solar cells. On 6-inch full-area solar cells (215.3 cm2 aperture area) open circuit voltages, fill factors and efficiency values of 738 mV, 81.4% and 23.2% were obtained, respectively; for 4 cm2 cell size the best obtained values in equivalent solar cells were 741 mV, 80.6% and 23.2%.
关键词： silicon heterojunction solar cells,texturing,ozone cleaning,surface passivation
更新于2025-09-12 10:27:22
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Facile Formation of 2D-3D Heterojunctions on Perovskite Thin Film Surfaces for Efficient Solar Cells
摘要： The interfaces between perovskite and charge transport layers greatly impact the device efficiency and stability of perovskite solar cells (PSCs). Inserting an ultrathin wide bandgap layer between perovskite and hole transport layers (HTL) has recently been shown as an effective strategy to enhance device performance. Herein, a small amount of organic halide salt, N,N’-dimethylethylene-1,2-diammonium iodide, is used to create 2D-3D heterojunctions on MAPbI3 thin film surfaces by facile solution processing. The formation of ultrathin wide bandgap 2D perovskite layer on top of 3D MAPbI3 changes the morphological and photophysical properties of perovskite thin films, effectively reduces the surface defects, and suppresses the charge recombination in the interfaces between perovskite and HTL. As a result, a power conversion efficiency of ~ 20.2%, with an open circuit voltage of 1.14 V, a short-circuit current density of 22.57 mA cm-2, and a fill factor of 0.78, is achieved for PSCs with enhanced stability.
关键词： Perovskite solar cells,2D-3D heterojunctions,interface engineering,stability,surface passivation
更新于2025-09-12 10:27:22
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Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon
摘要： We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the mc-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (NLP) from 50 to 1200, the average size of the PbS-NPs was varied from ~2 nm to ~10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify NLP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as ~430 μs versus 40 μs for the bare treated PS layer and 2.2 μs for the untreated bare mc-Si).
关键词： Pulsed laser deposition,Porous silicon,Solar cells,PbS nanoparticles,Surface passivation
更新于2025-09-12 10:27:22
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SnO2 surface defects tuned by (NH4)2S for high-efficiency perovskite solar cells
摘要： Tin oxide (SnO2) is widely adopted as an electron transport layer (ETL) in perovskite solar cells (PSCs). However, the oxygen vacancies of the SnO2 not only are the trap states of the nonradiative recombination of photo-generated carriers, but also build the potential barrier of carrier transport. To solve this issue, ammonium sulfide [(NH4)2S] is introduced to the SnO2 precursor for passivating the surface defects by terminating the Sn dangling bonds (S–Sn bonds). After reducing the surface traps, the electron mobility and conductivity of SnO2 film are enhanced significantly while the carrier recombination is decreased. Additionally, the energy level of S-SnO2 is also slightly modified. Therefore, this sulfide-passivated mothed remarkably improves the electron collection efficiency of the ETL. Furthermore, the linkage of Sn–S–Pb anchors the perovskite crystals at the perovskite/SnO2 interface, which increases the electron extraction efficiency and the stability of PSC. Based on this S-SnO2 ETL, the power conversion efficiency of the PSC is greatly promoted from 18.67% to 20.03%, compared with the reference one. In this study, it is proven that the surface defect passivation of SnO2 is an efficient and simple method to improve the photovoltaic performance, as a promising ETL for high-efficiency device.
关键词： Oxygen vacancy,Carrier transport dynamic,SnO2 electron transport layer,Surface passivation,Perovskite solar cells
更新于2025-09-12 10:27:22
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Strategy toward ultra-high-resolution micro-LED displays by bonding interface-engineered vertical stacking and surface passivation
摘要： In this paper, we have proposed the strategy to fulfill the vertically stacked subpixel (VSS) micro-light-emitting diodes (μ-LEDs) for future ultra-high resolution microdisplays. At first, to vertically stack the LED with different colors, we have successfully adopted the bonding interface engineered monolithic integration method by using SiO2/SiNx distributed Bragg reflectors (DBRs). It was found that an intermediate DBR structure can be performed as the bonding layer and the color filter, which can reflect and transmit desired wavelengths the bonding interface. Furthermore, the optically pumped μ-LEDs array with 0.4 μm pitch corresponding to ultra-high-resolution of 63500 PPI was successfully fabricated by using typical semiconductor processing, including electron-beam lithography. Compared with pick-and-place with the limitation of the machine alignment accuracy, there is a significant improvement for fabricating the high-density μ-LEDs. Finally, we have systematically investigated the effects of surface traps by using time-resolved photoluminescence (TRPL) and two-dimensional simulation. These results clearly demonstrated that performance improvements could be possible by employing the optimal passivation techniques according to diminishing the pixel size for low power and highly-efficient microdisplays.
关键词： ultra-high-resolution,micro-LEDs,wafer bonding,distributed Bragg reflectors,surface passivation
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Low-temperature silicon surface passivation for bulk lifetime studies based on Corona-charged Al2O3
摘要： Bulk lifetime studies of crystalline silicon wafers, e.g. with the aim of studying the light-induced degradation and regeneration behavior, require low-temperature surface passivation schemes that do not alter the silicon bulk properties, e.g. through hydrogenation. Aluminum oxide (Al2O3) can provide an excellent and stable surface passivation, however, in order to achieve the best possible surface passivation, an annealing step at ~400°C is typically required, which has been found to alter the bulk properties of some silicon materials. Hence, in this contribution we examine the possibility of passivating the silicon surface using Al2O3 layers that have seen a much lower thermal budget. We demonstrate that we are able to achieve an excellent silicon surface passivation using atomic-layer-deposited Al2O3 with measured effective surface recombination velocities Seff as low as 1.3 cm/s without exceeding a temperature of 250°C. We are able to achieve such excellent low-temperature passivation by applying a post-deposition annealing step at 250°C in combination with the deposition of negative Corona charges on the Al2O3 surface. For samples annealed at only 220°C, we still reach very low Seff values of 2 cm/s after deposition of negative Corona charges. We demonstrate that the Corona-charged low-temperature Al2O3 passivation shows only a slight degradation from an Seff of 1.6 cm/s to an Seff of 5 cm/s after 218 days of storage. Even without any post-deposition anneal and only negative Corona charges deposited, we achieve stable Seff values of 15 cm/s. As an alternative to Corona charging, a short exposure to intense UV light (λ = 395 nm) also significantly improves the surface passivation quality of low-temperature-annealed Al2O3-passivated silicon samples. However, the best surface passivation for the latter method is limited to an Seff value of 6.6 cm/s, which is still quite reasonable for bulk lifetime studies.
关键词： bulk lifetime studies,Al2O3,Corona charging,silicon surface passivation,low-temperature annealing
更新于2025-09-11 14:15:04
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In-situ Process to Form Passivated Tunneling Oxides for Front-surface Field in Rear-emitter Silicon Heterojunction Solar Cells
摘要： A novel approach involving CO2 plasma treatment of intrinsic hydrogenated amorphous silicon was developed to form ultra-thin silicon oxide (SiOx) layers, that is, passivated tunneling layers (PTLs), for the fabrication of passivated tunneling contacts. These contacts were formed by depositing the PTL/n-type hydrogenated nano-crystalline layer (nc-Si:H(n))/c-Si(n) stacks. The results indicated that a higher CO2 plasma treatment pressure was preferred for the formation of oxygen-richer components in the silicon oxide films, with Si2+, Si3+, and Si4+ peaks, and a smoother PTL/c-Si heterointerface. The PTLs with higher oxidation states and lower surface roughness exhibited advantages for the c-Si surface passivation, with a maximum implied open-circuit voltage of approximately 743 mV. The lowest contact resistivity of approximately 60 mΩcm2 was obtained using nc-Si:H(n)/PTL/c-Si(n) as the passivated tunneling contact. Most importantly, the in-situ process can help prevent the contamination of the heterointerface during device fabrication processes.
关键词： Passivated tunneling layer (PTL),Silicon oxide (SiOx),CO2 plasma treatment,Silicon surface passivation
更新于2025-09-11 14:15:04
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Manipulation of Phase-Transfer Ligand-Exchange Dynamics of PbS Quantum Dots for Efficient Infrared Photovoltaics
摘要： Chemical surface treatment of colloidal quantum dots (CQDs) by phase-transfer ligand exchange (PTLE) is essential to implement highly densified, well-passivated CQD films for optoelectronic applications, such as infrared photovoltaics, light-emitting diodes and photodetectors. The PTLE, however, involves parallel and interactional processes of ligand exchange, phase transfer, and surface passivation of CQDs, which renders the optimization of PTLE still challenging. Herein, we explored the action mechanism of a widely-used additive, ammonium acetate (AA), on the PTLE of PbS CQDs in order to recognize the dynamic balance during the PTLE process and its impact on the performance of colloidal quantum dot solar cells (CQDSCs). Our research definitely shows that AA additive can modify the dynamics of PTLE by participating in all the three processes, and the amount of AA significantly influences the defect passivation and colloidal stability of PbS CQDs. At an appropriate concentration (~50 mM) of AA, PbS CQDs are well iodide-passivated by the PTLE, and the fabricated CQDSCs achieve the PCE of ~10% associated with the improved carrier transport and the reduced trap-assisted carrier recombination. However, excessive AA causes the trace residual AA on the CQD surface, resulting in the insufficient surface passivation of PbS CQDs and trap issues of CQDSCs. The double-edged sword effect of AA additive on the PTLE, demonstrated in our work, suggests that realizing the dynamic balance of different processes during PTLE is crucial for the further performance promotion of CQDSCs.
关键词： infrared photovoltaics,ammonium acetate,phase-transfer ligand exchange,colloidal quantum dots,surface passivation
更新于2025-09-11 14:15:04
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Self-assembled Fluorinated Polymer Passivation Layer for Efficient Perovskite Thin-film Solar Cells
摘要： We report the fabrication of self-assembled surface-passivated [CH(NH2)2]0.8Cs0.2PbI3 thin films using a one-step method with a fluorinated polymer (FP) as an additive without post-treatment. The FP phase is separated and aggregated at the top surface of the perovskite layer during film formation. This FP acts as a passivation layer and improves the short-circuit current density and the fill factor consequently, the power conversion efficiency increases from 17.2% for the FP-free device to 19.1% for the 4-mg/mL-FP-added device.
关键词： Perovskite solar cells,Surface Passivation,Fluorinated Polymer
更新于2025-09-11 14:15:04
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Annealing Impact on Interface Properties of Sprayed Al2O3-Based MIS Structure for Silicon Surface Passivation
摘要： Aluminum oxide (Al2O3) films of different thicknesses were deposited on quartz and silicon (100) substrates by an ultrasonic spray method from a solution of aluminum acetylacetonate dissolved in N,N-dimethylformamide with different molar concentrations. The optical, morphological and electrical properties were investigated. Increasing the molar concentration leads to a refractive index decrease, an increase in the optical band gap from 5.26 eV to 5.52 eV and a change in the surface roughness of the films. The electrical parameters at the Al2O3/Si interface such as the flat band voltage (VFB), effective charge density (Qeff) and interface trap density (Dit) were explored as a function of the molar concentration, film thickness and heat treatment. The latter, done by two annealing processes, namely, the post deposition annealing (PDA) and post metallization annealing (PMA) on the structure, lead to remarkable interface properties. It was found that the positive flat band voltage VFB shift is correlated with the generation of negative effective charge during PMA. A decrease of the Dit distribution in the PMA samples with no significant effect in the case of PDA samples was clearly observed for different molar concentrations. Furthermore, as the Al2O3 film thickness decreases, Dit decreases in both PDA and PMA samples while the relatively high density Qeff and its negative charge polarity were obtained for thinner films. A noticeable passivation effect on the Al2O3/Si interface has been confirmed on samples that underwent the annealing process. These findings related specifically to the interface properties are promising for silicon surface passivation, in particular for solar cells applications.
关键词： Al2O3,surface passivation,ultrasonic spray,post-metallization annealing,post-deposition annealing
更新于2025-09-10 09:29:36