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Low-Temperature Aging Provides 22% Efficient Bromine-Free and Passivation Layer-Free Planar Perovskite Solar Cells
摘要： Previous reports of formamidinium/methylamine (FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example, through the inclusion of bromine and surface passivation. In this paper, we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase. Through low-temperature aging growth (LTAG) of a freshly deposited perovskite film, α-phase perovskites can be seeded in the intermediate phase and, at the same time, prevent beta-phase perovskite to nucleate. After postannealing, large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained, thereby eliminating the need of additional surface passivation step. Our pristine LTAG-treated solar cells could provide PCEs of greater than 22% without elaborate use of bromine or an additional passivation layer. More importantly, when using this LTAG process, the growth of the pure alpha-phase FAMAPbI3 was highly reproducible.
关键词： Perovskite solar cells,Bromine-free,Passivation layer,Lead iodide,Aging growth
更新于2025-09-23 15:21:01
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Thermionic Emission-Based Interconnecting Layer Featuring Solvent Resistance for Monolithic Tandem Solar Cells with Solution-Processed Perovskites
摘要： All-perovskite tandem cells have been considered a potential candidate for bringing the power conversion efficiency (PCE) beyond the Shockley– Queisser limit of single-junction device while retaining the advantages of earth-abundant materials and solution processability. However, a challenging issue with regard to realizing such solution-processed devices is the fulfillment of complex and coupled requirements of the interconnecting layer (ICL), including solvent resistance to protect underlying perovskite film, high electrical properties for carrier transport and recombination, and high optical transmission. In this work, a new thermionic emission–based ICL with enhanced solvent resistance features is demonstrated. Fundamentally, the thermionic emission plays a critical role in the electron transport process in the ICL, which is confirmed through both experimental and theoretical studies. Besides achieving high optical transmission and electrical properties, the new ICL chemically protects the underlying perovskite film by introducing a fluoride silane– incorporated polyethylenimine ethoxylated hybrid system that also passivates the surface defects to reduce electrical loss. The monolithic all-perovskite tandem cells demonstrate highest PCE of 17.9% (from current density–voltage scan) and the highest steady-state efficiency is 16.1% for a typical device. Consequently, this work contributes to not only understanding the fundamental mechanism of ICLs but also promotes robust and low-cost photovoltaics.
关键词： monolithic all-perovskite tandem solar cells,solvent resistance,interconnecting layer,thermionic emission,defect passivation
更新于2025-09-23 15:21:01
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Role of hydrogen in modifying a-Si:H/c-Si interface passivation and band alignment for rear-emitter silicon heterojunction solar cells
摘要： Boosting the contact property of intrinsic hydrogenated amorphous silicon (a-Si:H(i)) film is pivotal to achieving high-efficiency silicon heterojunction (SHJ) solar cells. Here, the microstructure of a-Si:H(i) film is modified with hydrogen dilution ratio using hot wire chemical vapor deposition (HWCVD) for the application into rear-emitter SHJ solar cells. A higher hydrogen content associated with high valence band offset was found to decrease the fill factor FF for low dilution, while high interface defect densities related to epitaxial growth are responsible for the deterioration of both FF and open-circuit voltage VOC for high dilution. In particular, the most compact film prepared at a moderate dilution exhibits the most compact structure with most hydrogen located as isolated hydrogen rather than clustered hydrogen. Finally, high efficiency of SHJ solar cells up to 22.5% was yielded using the optimized a-Si:H(i) layer thanks to a significant enhancement of FF, which is attributed to improved passivation quality and rational band alignment at the a-Si:H(i)/c-Si interface. This work clearly interpreted the correlation between SHJ device parameters and a-Si:H(i)/c-Si interface properties, which might guide the design of a-Si:H passivation layers in pursuit of high-efficiency SHJ solar cells.
关键词： HWCVD,hydrogen dilution,SHJ solar cells,a-Si:H(i),passivation,band alignment
更新于2025-09-23 15:21:01
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Mixed 2D/3D perovskite with fine phase control modulated by a novel cyclopentanamine hydrobromide for better stability in light-emitting diodes
摘要： The mixed 2D/3D perovskite has been proved to be a promising candidate to increase the exciton binding energy in perovskite light-emitting diodes (PeLEDs). However, the complex phase distribution and impurity (usually referring to ligands) limit the stability of the corresponding PeLEDs. Here, a novel molecule, cyclopentanamine hydrobromide (CyPA·HBr), is adopted to construct a mixed 2D/3D perovskite by partial substitution of FA with CyPA, realizing fine phase control for improved device stability. The adoption of CyPA·HBr helps to tune perovskite grain growth and passivate the defect, resulting in high coverage and smooth thin film with improved photoluminescence property. The PeLEDs with an optimized CyPA·HBr concentration of a molar ratio of 40% exhibit a pure green emission with a full width at half maximum of 22 nm, an external quantum efficiency of 6.55%, and a maximum brightness of 9408 cd m?2 simultaneously. Interestingly, the CyPA·HBr-based device shows a half-lifetime two times longer than the one based on the most commonly used ligand of phenethylammonium bromide (PEA·HBr), assigned to the better phase control ability of CyPA·HBr in 2D/3D perovskite. Those results testify the importance of ligands to modulate perovskite phase along with efficient passivation defects for better stability of PeLEDs.
关键词： Phase control,Stability,Perovskite,Light-emitting diode,Defect passivation
更新于2025-09-23 15:21:01
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Morphological and optoelectronic investigations of CsPbBr3 nanocrystals chelating diphenylammonium halide ligands via low temperature synthesis
摘要： In this study, the low temperature method was adopted to synthesize all-inorganic cesium lead bromide CsPbBr3 nanocrystals (NCs) as the active layer in light-emitting devices. In order to improve film-forming and optoelectronic properties of CsPbBr3 NCs, a surface ligand diphenylammonium bromide (DPABr) was added from 0 to 0.15 mole fraction in proportion to the amount of oleylamine. The experimental results showed that introducing 0.1 mole fraction of DPABr in CsPbBr3 NCs brought the best performance. The SEM and AFM results revealed that smooth and pinhole-free films of CsPbBr3 NCs were formed by introducing DPABr with a low surface roughness of 4.6 nm. The introduced bromide ions can passivate the surface vacancies of CsPbBr3 NCs and improve photoluminescence quantum yield (PLQY) from 38% to 72% compared with the pristine CsPbBr3 NCs. Moreover, shorter and π electron-rich phenyl groups help to increase carrier injection into nanocrystalline core, preventing carriers from being hindered by oleic acid and oleylamine with longer alkyl chains. Therefore, the conductivity of the resulting CsPbBr3 NCs was augmented. The maximum brightness and current efficiency of the optimized device based on CsPbBr3 NCs with 0.1 mole fraction of DPABr were enhanced 2.3- and 3.3-fold, respectively, relative to the pristine one.
关键词： perovskite nanocrystals,low temperature method,photoluminescence quantum yield,surface passivation,diphenylammonium bromide
更新于2025-09-23 15:21:01
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Surface passivation enabled-structural engineering of I-III-VI <sub/>2</sub> nanocrystal photocatalysts
摘要： Cation exchange has evolved into a powerful tactic for synthesis of semiconductor nanocrystals (NCs) that are not readily accessible otherwise. Here we have investigated the In3+-for-Cu+ cation exchange in the dodecahedral-shaped Cu7S4 NCs and found that surface passivation, either caused by excess guest cations or ligand molecules, can be exploited to engineer the structural properties of the NCs. By monitoring the parallel reactions carried out under systematically varied conditions, together with the positron annihilation spectroscopy investigation, we have demonstrated that the key element accounting for the observed surface passivation is associated with the copper vacant sites on the surface of Cu7S4 NCs. The reduction in In3+/Cu+ ratio and the presence of strong-binding ligands could enhance the density of surface copper vacancies and boost cation exchange reaction, which therefore alters the competition between the in-di?usion of In3+ and out-di?usion of Cu+ ions. Such capability to control the inter-di?usion balance in cation exchange (and the accompanying Kirkendall e?ect) enables the creation of a series of CuInS2 (and Cu7S4@CuInS2) NCs with various exotic structures, which show di?erent photocatalytic abilities in singlet oxygen generation. This study can not only add more structural complexity and diversity to the semiconductor NCs achievable by cation exchange, but also presents an important guideline for establishing a unifying mechanistic understanding of the reaction kinetics in cation exchange process.
关键词： cation exchange,Kirkendall effect,semiconductor nanocrystals,photocatalysis,surface passivation
更新于2025-09-23 15:21:01
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Improving the leakage characteristics and efficiency of GaN-based micro-light-emitting diode with optimized passivation
摘要： We investigated the effect of atomic layer deposition (ALD) Al2O3 (50 nm)/plasma-enhanced chemical vapour deposition (PECVD) SiO2 (250 nm) and PECVD SiO2 (300 nm) passivation layers on the leakage current and efficiency of InGaN-based micro-LEDs with different sizes. The micro-LEDs with the single passivation layer gave the ideality factors of about 2.0, while that with the double layer exhibited values smaller than 2.0. The micro-LEDs with the double passivation layer exhibited external quantum efficiency peaks at lower current density compared to those with the single layer. It was shown that smaller micro-LEDs were more sensitively dependent on the types of the passivation layers. These results exhibit that the ALD-Al2O3/PECVD-SiO2 passivation layer is more effective in suppressing the sidewall damage-induced current than the PECVD-SiO2 layer.
关键词： Atomic layer deposition,Micro-LED,Passivation,GaN
更新于2025-09-23 15:21:01
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Engineering of Electron Extraction and Defects Passivation via Anion Doped Conductive Fullerene Derivatives as Interlayers for Efficient Invert Perovskite Solar Cells
摘要： The major limitation of organic-inorganic perovskite solar cells performance is the existence of numerous charged defects at the absorption layer surface, which caused charge carrier recombine depravation. These defects have remarkable influence on the charge extraction, which further caused the instability of device and induce severe hysteresis. Here, three low-cost anion-doping conductive fullerene derivatives, fullerene bis(phenethyl alcohol) malonate (FMPE-I), fullerene bis(ethylenediamine) malonamide (FEDA-I), and fullerene bis(propanediamine) malonamide (FPDA-I), are developed for the first time as interfacial layers between a perovskite and phenyl-C61-butyric acid methyl ester (PCBM) in planar invert perovskite solar cells under mild solution fabrication. The constituent Lewis basic halides and the specific amide groups of conductive fullerene derivatives efficaciously heighten the chemical interaction between the perovskite and conductive fullerene derivatives since the iodide can combine with under-coordinated Pb2+ by electrostatic interaction and amide group can facilely combined with I by hydrogen bonding, improving the dual-passivation of perovskite defects. Moreover, due to the well-matched energy level of conductive fullerene derivatives and the high conductivity of the perovskite/interlayer film, the electron extraction capacity can be effectively enhanced. Consequently, superior optoelectronic properties are achieved with an improved power conversion efficiency of 17.63%, which is considerably higher than that of the bare PCBM based devices (14.96%), for the perovskite device with conductive interlayer treatment along with a negligible hysteresis. Moreover, hydrophobic conductive fullerene derivatives improve the resistance of device to moisture. The conductive fullerene derivative-based devices without encapsulation are maintained at 85% of the pristine power conversion efficiency value after storage in ambient conditions (25 oC temperature, 60% humidity) for 500h.
关键词： dual-passivation,energy level alignment,perovskite solar cells,Conductive fullerene derivatives,interface engineering
更新于2025-09-23 15:21:01
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Passivation of defects in inverted perovskite solar cells by imidazolium-based ionic liquid
摘要： During perovskite film preparation, defects in the film are almost impossible to avoid because of the migration of the halide ions, which is detrimental to achieve high-quality film. In general, the introduction of additive is an effective strategy to control the film morphology and to reduce the defect density. Here, a representative and simplest ionic liquid, 1-methyl-3-propylimidazolium bromide (MPIB), is selected as an additive due to its high conductivity and lone-pair electron in its cation group. Remarkably, the adding of MPIB additive into the perovskite film improves the power conversion efficiency (PCE) from 15.9% of pristine device to 18.2%. With the help of characterization analysis of scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, etc., two contributions of MPIB additive are addressed: (1) the major one is the passivation of the uncoordinated Pb2+ to reduce the defects in the perovskite film due to the lone-pair electron in its cation group, and (2) the secondary one is beneficial to promote crystal growth to improve the film quality. Hence, this work provides an easy approach to achieve high-performance perovskite solar cell via passivation of the uncoordinated Pb2+ in the perovskite film due to the lone-pair electron in the cation group.
关键词： MPIB,ionic liquid,perovskite solar cells,power conversion efficiency,defect passivation
更新于2025-09-23 15:21:01
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Interface passivation treatment by halogenated low-dimensional perovskites for high-performance and stable perovskite photovoltaics
摘要： The voltage loss which is mainly caused by the nonradiative recombination at the interface has played a serious negative effect on the photovoltaic performance of perovskite solar cells (PSCs). Herein, we firstly designed four halogenated layers by the way of employing different benzylammonium-based aromatic cations for high-performance devices. The introduction of halogen functional groups can not only enhance the hydrophobicity but also optimize the photovoltaic characteristics of LDP which play an important role on passivation effect of the interface between perovskite and hole transport materials (HTM) layer. The films with halogenated LDP passivation layers displayed suppressed nonradiative recombination and reduced trap density, leading to significantly reduced voltage loss. As a result, the optimal devices with 4-bromobenzylammonium-based LDP layer achieved the power conversion efficiency (PCE) as high as 21.13% with an enhanced open-circuit voltage (Voc) of 1.14 V. Under the hydrophobic and buffer action of the halogenated LDP layer, the modified devices showed outstanding long-term stability when exposed to moisture, heat and continuous UV irradiation. This work proves the enhanced passivation effect of LDP layer by regulating the chemical property of introduced organic cations for high-performance and stable perovskite photovoltaics.
关键词： Low-dimensional perovskite,Perovskite solar cells,Halogenated cations,Passivation effect,Photovoltaic performance
更新于2025-09-23 15:21:01