Passivation Of Solar Cells Research Articles

Deep level defect passivation for printable mesoporous CsSnI3 perovskite solar cells with efficiency above 10%

The lead-free inorganic perovskite CsSnI3 is considered as one of the best candidates for emerging photovoltaics. Nevertheless, CsSnI3-based perovskite solar cells experience a significant drop in performance due to the nonradiative recombination facilitated by trapping. Here, we show an electron donor passivation method to regulate deep-level defects for CsSnI3 perovskite with electron donor pyrrole. Experimental observations combined with theoretical simulations verify that the saturation of Tin dangling bonds with pyrrole on the CsSnI3 surface via a Lewis acid-base addition reaction can significantly reduce the density of deep-level defects. Consequently, the printable mesoporous perovskite solar cells with an FTO/compact-TiO2/mesoporous-TiO2/Al2O3/NiO/carbon framework device structure penetrated with CsSnI3 achieve a power conversion efficiency of up to 10.11%. To our knowledge, this represents the highest efficiency reported to date for lead-free perovskite-based printable mesoporous solar cells. Furthermore, the unencapsulated devices demonstrated remarkable long-term stability, retaining 92% of their initial efficiency even after 2400 h of aging in a nitrogen atmosphere.

Enhancing efficiency through surface passivation of carbon-based perovskite solar cells

Perovskite solar cells (PSCs) have made significant strides in power conversion efficiency (PCE), but their commercialization remains limited by stability issues. Additionally, the high cost of electrodes like gold necessitates the exploration of more affordable alternatives such as carbon (graphene). In this study, we present an approach that combines material dimensionality control and interfacial passivation using post-device treatment with phenethylammonium iodide (PEAI), an organic halide salt, to enhance the efficiency of carbon-based PSCs. Effective defect passivation is key to further improving the PCE and open-circuit voltage (VOC) of PSCs. Our results show that PEAI successfully passivates defects on the perovskite surface, significantly reducing non-radiative recombination. As a result, we achieved carbon-based PSCs with an impressive efficiency of 19.3%, demonstrating excellent stability under maximum power point tracking (MPPT) for over 900 h.

Simple Smoothing of the Bottom Silicon Surface Using Wet Chemical Etching Methods for Epitaxial III‐V/Silicon Tandem Manufacturing

The implementation of diverse technologies has recently facilitated the production of cost‐effective and highly efficient solar cells. High‐efficiency solar cells with III‐V compounds tandem crystalline silicon cells have achieved photovoltaic efficiency of higher than 39%. Etching silicon wafers plays a vital role in the deposition of epitaxial layers, neutralizing dangling bonds, and surface passivation for tandem solar cells. The wafers are polished using a solution of HF–HNO3–CH3COOH (HNA) and 20% KOH to smoothen the wafer surface. When HNA wet etching is performed for 3.5 min and the 20% KOH etching lasts for 6 min, the microroughness of the wafer is 1.9 nm with a measurement area of 10 × 10 μm2 and 0.816 nm within an area of 1 × 1 μm2. Compared with the as‐cut wafer, the reflectance increases from 31.7% to 34.7%, and the effective minority carrier lifetime, with 30 nm Al2O3 passivation after 450 °C activated, increases from 1.4 to 1.8 ms in a carrier density of 1.0 × 1015 cm−3.

Ultrathin Self-Assembled Monolayer for Effective Silicon Solar Cell Passivation.

Passivation technology is crucial for reducing interface defects and impacting the performance of crystalline silicon (c-Si) solar cells. Concurrently, maintaining a thin passivation layer is essential for ensuring efficient carrier transport. With an ultrathin passivated contact structure, both Silicon Heterojunction (SHJ) cells and Tunnel Oxide Passivated Contact (TOPCon) solar cells achieve an efficiency surpassing 26%. To reduce production costs and simplify solar cell manufacturing processes, the rapid development of organic material passivation technology has emerged. However, its widespread industrial production is hindered by environmental safety concerns, such as strong acid corrosion and biological and ecological safety issues. Here, we discovered a low-cost self-assembled monolayer (SAM) hole-selective transport material known as 2PACz ([2-(9H-carbazol-9-yl) ethyl] phosphonic acid) with phosphate groups to form c-Si solar cells for the first time. The ultrathin film of 2PACz with phosphate groups can establish strong and stable P-O-Si bonds on the silicon surface. Meanwhile, like 2PACz, a uniform ultrathin film with a carbazole function group can offer electron-localizing and thus hole-selective properties, which provides ideas for studying dopant-free silicon solar cells. As a result of such interfacial passivation engineering, it plays an important role in repairing porous structures, such as pyramid-textured silicon surfaces, and cutting losses during the commercialization of c-Si solar cells. Crucially, this advancement offers insights for the development of new high-efficiency ultrathin film passivation methods in the postsilicon era.

Isomeric diammonium passivation for perovskite-organic tandem solar cells.

In recent years, perovskite has been widely adopted in series-connected monolithic tandem solar cells (TSCs) to overcome the Shockley-Queisser limit of single-junction solar cells. Perovskite/organic TSCs, comprising a wide-bandgap (WBG) perovskite solar cell (pero-SC) as the front cell and a narrow-bandgap organic solar cell (OSC) as the rear cell, have recently drawn attention owing to the good stability and potential high power conversion efficiency (PCE)1,2,3,4. However, WBG pero-SCs usually exhibit higher voltage losses than regular pero-SCs, which limits the performance of TSCs5,6. One of the major obstacles comes from interfacial recombination at the perovskite/C60 interface, and it is important to develop effective surface passivation strategies to pursue higher PCE of perovskite/organic TSCs7. Here we exploit a new surface passivator cyclohexane 1,4-diammonium diiodide (CyDAI2), which naturally contains two isomeric structures with ammonium groups on the same or opposite sides of the hexane ring (denoted as cis-CyDAI2 and trans-CyDAI2, respectively), and the two isomers demonstrate completely different surface interaction behaviors. The cis-CyDAI2 passivation treatment reduces the Quasi-Fermi level splitting (QFLS)-open circuit voltage (Voc) mismatch of the WBG pero-SCs with a bandgap of 1.88 eV and enhanced its Voc to 1.36 V. Combining the cis-CyDAI2 treated perovskite and the organic active layer with a narrow-bandgap of 1.24 eV, the constructed monolithic perovskite/organic TSC demonstrates a PCE of 26.4% (certified as 25.7%).

Grain boundary defect passivation and iodine migration inhibition for efficient and stable perovskite solar cells

To inhibit the I−migration and passivate the uncoordinated Pb2+ on perovskite grain boundary (GB), 3-methyl-(1,1′-biphenyl)-4,4′-diformaldehyde (BPDA-Me) and 3-chlorine-(1,1′-biphenyl)-4,4′-diformaldehyde (BPDA-Cl) were synthesized and incorporated into perovskite films, respectively. The C = O groups in both additives can strongly interact with the uncoordinated Pb2+, allowing them to be anchored in perovskite GB. At the same time, the benzene ring skeleton in these two molecular structures can interact with the migrating I− in GB. The Cl atom in the BPDA-Cl molecule delocalize electrons into the C = O group due to the conjugation effect of the benzene ring, so that the C = O group can provide stronger electronegativity, thus enhancing the interaction with the uncoordinated Pb2+. Meanwhile, Cl atom can coordinate with Pb2+ to synergically passivate the I vacancy defect on GB and enhance the lattice strength of PbI6. This cooperative passivation further effectively inhibited the I−migration occurring at the perovskite GB. The functional group electron density regulation and cooperative passivation of Cl and C = O in BPDA-Cl make the passivation effect better than BPDA-Me. Consequently, the BPDA-Cl based perovskite solar cell achieved the highest power conversion efficiency of 24.96 % and stability with 92.1 % of the initial performance retained after 500 h of operation under continuous lighting and maximum power point tracking conditions.

Multifunctional Guanidine Ionic Liquid with Lactate Anion-Assisted Crystallization and Defect Passivation for High-Efficient and Stable Perovskite Solar Cells

Multifunctional Guanidine Ionic Liquid with Lactate Anion-Assisted Crystallization and Defect Passivation for High-Efficient and Stable Perovskite Solar Cells

Polymer-assisted crystal growth regulation and defect passivation for efficient perovskite solar cells

Polymer-assisted crystal growth regulation and defect passivation for efficient perovskite solar cells

Characterization of rear-side potential-induced degradation in bifacial p-PERC solar modules

Bifacial solar modules are increasingly preferred over monofacial modules to maximize the solar power output within a limited space. Owing to their high efficiency and compatibility with existing production lines, bifacial p-type passivated emitter and rear contact (p-PERC) solar modules have dominated the market since their commercialization. This study analyzes the influence of Al2O3, a passivation layer of p-PERC solar cells, on the PID and its underlying mechanism. Experiments were conducted on bifacial p-PERC module samples to analyze their electrical properties. Additionally, cell-like samples were fabricated to measure characteristics, for example, carrier lifetime, that are difficult to assess in full modules. To accelerate module degradation, experiments were conducted at 85 °C and 85 % humidity, while a voltage of −1000 V was applied to investigate the PID phenomenon. The results reveal degradation at the rear of the module caused by polarization effects, which were confirmed through changes in solar cell parameters and recombination current. The proposed mechanism indicates that the degradation in bifacial p-PERC solar modules is caused by the field-effect deterioration of the Al₂O₃ layer caused by alkali ions diffusing from the glass. This is observed through changes in the carrier concentration within Si and the detection of alkali ions within Al2O3. Our analysis considers both module and cell structure samples to delineate the influence of Al2O3 on the PID, which has not been previously reported. This study enhances the understanding of the polarization effect in bifacial p-PERC solar cells, thus contributing to the advancement of solar cell passivation strategies.

Multifunctional molecular bridge enabled interface passivation and strain release for stable and efficient all-inorganic perovskite solar cells

The precise management of the buried interface in n-i-p perovskite solar cells (PSCs) to achieve efficient charge extraction and transport is crucial for improving the photovoltaic performance. Here, a 4-chloro-2,5-dimethoxyaniline (CDA) modifier with multifunctional groups is utilized as a molecular bridge at the TiO2/CsPbBr3 buried interface to enhance the qualities of TiO2 and CsPbBr3 films and the arrangement of interface energy level. The chlorine atom in CDA can heal the oxygen vacancies defects on the TiO2 film surface, thereby improving its electron mobility and conductivity. The –O– and -NH2 groups in CDA play a passivation effect on the ions defects of CsPbBr3 film, and especially the two –O– groups can anchor the lattice Pb atoms of CsPbBr3 perovskite, which effectively reduce the trap states of CsPbBr3 film and release the residual lattice strain. The modification of CDA also improves the wettability and energy level of TiO2 film to optimize CsPbBr3 crystal growth and charge transport, respectively. Consequently, the CsPbBr3 PSCs with CDA molecular bridge free of encapsulation achieve a highly increased power conversion efficiency of 10.85%, in contrast with 8.16% value of the control device. After 720 h of storage at 85 °C and in air environment with 85% relative humidity, the efficiency of the CDA-modified device retains 93.1% of the initial value, demonstrating excellent long-term humidity and thermal stability.

Molecule-triggered strain regulation and interfacial passivation for efficient inverted perovskite solar cells

Molecule-triggered strain regulation and interfacial passivation for efficient inverted perovskite solar cells

Front Cover: Revealing the Roles of Guanidine Hydrochloride Ionic Liquid in Ion Inhibition and Defects Passivation for Efficient and Stable Perovskite Solar Cells (ChemSusChem 14/2024)

Front Cover: Revealing the Roles of Guanidine Hydrochloride Ionic Liquid in Ion Inhibition and Defects Passivation for Efficient and Stable Perovskite Solar Cells (ChemSusChem 14/2024)

Exploration HTL-Free all inorganic mixed halide perovskite solar cells: effects of 4-ADPA passivation

The incredible PV performance of thin-film perovskite solar cells has garnered the attention of researchers. Mixed halide perovskite outweighs pure halide perovskite in its ability to optimize PV performance while performing material composition engineering. All inorganic mixed halide (AIMH) perovskite CsPbI2Br has shown stable performance against thermal variations. This study mainly highlights the performance of HTL (Hole transport layer) free, passivated solar cell structure with utilization of the SCAPS-1D simulator. The inclusion of passivation layer 4-ADPA(4-aminodiphenylamine) between active layer CsPbI2Br and the end electrode mitigates the occurrence of charge carrier recombination. The thickness of passivation layer 4-ADPA is optimized for the range 100 nm–1000 nm, and 100 nm is decided as the optimum width based on the evaluated PV performance of SnO2/CsPbI2Br/4-ADPA/anode. 4-ADPA layer with an optimum thickness of 100 nm, is embedded with a CsPbI2Br layer, and the performance of solar cell has been investigated under the collective impact of BDD (bulk defect density)/thickness of CsPbI2Br for the range (1012 cm−3 to 1018 cm−3)/(50 nm to 500 nm) respectively. Further, this study investigated the capacitance–voltage (C-V), Mott—Schottky (1/C2), and Nyquist plot (C-F) performance of solar cells under the influence of only BDD for two cell configurations (corresponding to maximum and minimum delivered PCE i.e., thickness/BDD is 200 nm/1012 cm−3 and 500 nm/1018 cm−3 respectively). The highest 13.27% of PCE is extracted from HTL-free, 4-ADPA passivated all inorganic PSC, at 200 nm/1012 cm−3 of thickness/BDD respectively. This technique encourages researchers to explore more cost-effective, HTL-free passivated solar cell structures.

Research on the Performance of Fmoc-amino Acid Passivated Peroverskite Solar Cells

This study investigates the effect of surface passivation of chalcogenide solar cells by introducing Fmoc-Gly-OH amino acids. The results show that the moderate amount of Fmoc-Gly-OH modification can significantly improve the photovoltaic performance and stability of chalcogenide solar cells. With the increase of Fmoc-Gly-OH concentration, the photovoltaic conversion efficiency firstly increases and then decreases, and the best effect is reached when the concentration is 1.0 mg/ml.XRD and SEM analyses show that the crystal structure of the Fmoc-Gly-OH modified chalcocite thin films is more regular, and the defect density is obviously reduced.XPS analysis shows that the Fmoc-Gly-OH modification is able to reduce the defect state density of the chalcogenide layer. The reduction of defects was further verified by steady-state fluorescence spectroscopy analysis. In addition, the electrochemical impedance spectra and dark-state I-V curve results of the devices showed that the Fmoc-Gly-OH modification was able to reduce the non-radiative complexation and charge transport resistance, and increase the fill factor and open-circuit voltage. Finally, the effectiveness of Fmoc-Gly-OH surface passivation in enhancing the performance of chalcogenide solar cells was confirmed by the analysis of J-V curves and box plots. This study provides new ideas and methods for surface engineering of chalcogenide solar cells, which has some practical application prospects.

Silicon‐Inspired Analysis of Interfacial Recombination in Perovskite Photovoltaics

AbstractPerovskite solar cells have reached an impressive certified efficiency of 26.1%, with a considerable fraction of the remaining losses attributed to carrier recombination at perovskite interfaces. This work demonstrates how time‐resolved photoluminescence spectroscopy (TRPL) can be utilized to locate and quantify remaining recombination losses in perovskite solar cells, analogous to methods established to improve silicon solar cell passivation and contact layers. It is shown how TRPL analysis can be extended to determine the bulk and surface lifetimes, surface recombination velocity, the recombination parameter, J0, and the implied open‐circuit voltage (iVoc) of any perovskite device configuration. This framework is used to compare 18 carrier‐selective and passivating contacts commonly used or emerging for perovskite photovoltaics. Furthermore, the iVoc values calculated from the TRPL‐based framework are directly compared to those calculated from photoluminescence quantum yields and the measured solar cell Voc. This simple technique serves as a practical guide for screening and selecting multifunctional, passivating perovskite contact layers. As with silicon solar cells, most of the material and interface analysis can be done without fabricating full devices or measuring efficiency. These purely optical measurements are even preferable when studying bulk and interfacial passivation approaches, since they remove complicating effects from poor carrier extraction.

Defect Passivation and Crystallization Regulation for Efficient and Stable Formamidinium Lead Iodide Solar Cells with Multifunctional Amidino Additive.

Amidino-based additives show great potential in high-performance perovskite solar cells (PSCs). However, the role of different functional groups in amidino-based additives have not been well elucidated. Herein, two multifunctional amidino additives 4-amidinobenzoic acid hydrochloride (ABAc) and 4-amidinobenzamide hydrochloride (ABAm) are employed to improve the film quality of formamidinium lead iodide (FAPbI3) perovskites. Compared with ABAc, the amide group imparts ABAm with larger dipole moment and thus stronger interactions with the perovskite components, i.e., the hydrogen bonds between N…H and I- anion and coordination bonds between C = O and Pb2+ cation. It strengthens the passivation effect of iodine vacancy defect and slows down the crystallization process of α-FAPbI3, resulting in the significantly reduced non-radiative recombination, long carrier lifetime of 1.7 µs, uniformly large crystalline grains, and enhances hydrophobicity. Profiting from the improved film quality, the ABAm-treated PSC achieves a high efficiency of 24.60%, and maintains 93% of the initial efficiency after storage in ambient environment for 1200 hours. This work provides new insights for rational design of multifunctional additives regarding of defect passivation and crystallization control toward highly efficient and stable PSCs.

The use of ChatGPT to generate experimentally testable hypotheses for improving the surface passivation of perovskite solar cells

The use of ChatGPT to generate experimentally testable hypotheses for improving the surface passivation of perovskite solar cells

Light-absorber engineering induced defect passivation for efficient antimony triselenide solar cells

Antimony selenide (Sb2Se3) has attracted considerable attention thanks to non-toxic, earth-abundant and exceptional optoelectrical properties. Post-selenization treatment is a widely used approach to improve crystallization and passivate defects for chalcogenide thin-film solar cells. The overall performance of the final device is often significantly affected by the process conditions. Herein, we have systematically explored the influence of selenization pressure on Sb2Se3 thin-film solar cells fabricated via sputtering and post-selenization. High-quality Sb2Se3 thin films without visible voids and blisters have been obtained at an optimized selenization pressure of 0.05 Pa. The optimized Sb2Se3 absorber thin film not only mitigates charge carrier recombination but optimizes the back contact of the device. Consequently, a remarkable efficiency of 7.42 % was obtained for the champion device, paving a simple and effective way to fabricate superior Sb2Se3 absorber thin films and highly efficient solar cells. This study is expected to give insights into post-selenization operating conditions for device efficiency enhancement and to further expand the commercial application of Sb2Se3 thin-film solar cells.

Revealing the Roles of Guanidine Hydrochloride Ionic Liquid in Ion Inhibition and Defects Passivation for Efficient and Stable Perovskite Solar Cells.

As a result of full-scale ongoing global efforts, the power conversion efficiency (PCE) of the organic-inorganic metal halide perovskite has skyrocketed. Unfortunately, the long-term operational stability for commercialization standards is still lagging owing to intrinsic defects such as ion migration-induced degradation, undercoordinated Pb2+, and shallow defects initiated by disordered crystal growth. Herein, we employed multifunctional, non-volatile tetra-methyl guanidine hydrochloride [TMGHCL] ionic liquid (IL) as an additive to elucidate defects' passivation effects on organic-inorganic metal halide perovskite. More specifically, the formation of hydrogen bonds between H+ in GA+ and I- and coordinate bonding between Cl- and undercoordinated Pb2+ could significantly passivate these defects. The hypothesis was confirmed by both experimental and DFT simulations displaying that the optimized ratio of IL integration restrains ion migration, improving grains' size, and significantly elongating the carrier lifetime. Remarkably, the modified cell achieved a peak efficiency of 22.00 % with negligible hysteresis, compared to the control device's PCE of 20.12 %. In addition, the TMGHCL-based device retains its 93.29 % efficiency after 16 days of continuous exposure to air with a relative humidity of 35±5% and temperature of 25±5 °C. This efficient approach of adding IL to perovskites absorber can produce high PCE and has strong commercialization potential.

Effects on Metallization of n+-Poly-Si Layer for N-Type Tunnel Oxide Passivated Contact Solar Cells.

Thin polysilicon (poly-Si)-based passivating contacts can reduce parasitic absorption and the cost of n-TOPCon solar cells. Herein, n+-poly-Si layers with thicknesses of 30~100 nm were fabricated by low-pressure chemical vapor deposition (LPCVD) to create passivating contacts. We investigated the effect of n+-poly-Si layer thickness on the microstructure of the metallization contact formation, passivation, and electronic performance of n-TOPCon solar cells. The thickness of the poly-Si layer significantly affected the passivation of metallization-induced recombination under the metal contact (J0,metal) and the contact resistivity (ρc) of the cells. However, it had a minimal impact on the short-circuit current density (Jsc), which was primarily associated with corroded silver (Ag) at depths of the n+-poly-Si layer exceeding 40 nm. We introduced a thin n+-poly-Si layer with a thickness of 70 nm and a surface concentration of 5 × 1020 atoms/cm3. This layer can meet the requirements for low J0,metal and ρc values, leading to an increase in conversion efficiency of 25.65%. This optimized process of depositing a phosphorus-doped poly-Si layer can be commercially applied in photovoltaics to reduce processing times and lower costs.