低维钙钛矿太阳能电池的制备与光电性能研究——推荐一个综合化学实验

低维钙钛矿太阳能电池(Low-Dimensional Perovskite Solar Cells,LD PSCs)是一种稳定性好、疏水性强的新型钙钛矿光伏器件,在新能源领域受到了广泛的关注。本实验以领域内的前沿进展为出发点,提供丁胺(Butylammonium,BA)离子、半胱氨酸(2-氨基-3-巯基丙酸,Cysteine,Cys)离子作为有机间隔阳离子,合成了低维钙钛矿晶体并制备出以(BA)2(MA)n-1PbnI3n+1或(Cys)2(MA)n-1PbnI3n+1为活性层的钙钛矿太阳能电池,并通过X射线衍射检测、紫外-可见吸收检测等手段对产品进行表征,之后测定了钙钛矿器件的能量转换效率。本实验难度适中,涉及光伏器件的制备与表征,旨在激励本科生对前沿光电研究产生兴趣、培养其科研能力。

Two-Dimensional Materials for Highly Efficient and Stable Perovskite Solar Cells

Perovskite solar cells(PSCs)offer low costs and high power conversion efficiency.However,the lack of long-term stability,primarily stemming from the interfacial defects and the sus-ceptible metal electrodes,hinders their practical application.In the past few years,two-dimensional(2D)materials(e.g.,graphene and its derivatives,transitional metal dichalcogenides,MXenes,and black phosphorus)have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces,layer-dependent electronic band structures,tunable functional groups,and inherent compactness.Here,recent progress of 2D material toward efficient and stable PSCs is summarized,including its role as both interface materials and electrodes.We discuss their beneficial effects on perovskite growth,energy level alignment,defect passivation,as well as blocking external stimulus.In particular,the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized.Finally,perspectives on the further development of PSCs using 2D materials are provided,such as designing high-quality van der Waals heterojunction,enhancing the uniformity and coverage of 2D nanosheets,and developing new 2D materials-based electrodes.

Progress in Diagnosis and Treatment of Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth has been found to be associated with a variety of gastrointestinal disorders such as irritable bowel syndrome, inflammatory bowel disease, and, in recent years, diabetes mellitus and systemic sclerosis, among other extraintestinal diseases. Several novel diagnostic tools for small intestinal bacterial overgrowth have emerged in recent years, and several therapeutic approaches have been proposed. Therefore, it has become necessary to find an effective, safe, and simple diagnostic method and a safe treatment modality. This article provides a review of current diagnostic and therapeutic approaches to small intestinal bacterial overgrowth.

Solvent engineering towards scalable fabrication of high-quality perovskite films for efficient solar modules

Over the last decade,remarkable progress has been made in metal halide perovskite solar cells(PSCs),which have been a focus of emerging photovoltaic techniques and show great potential for commercialization.However,the upscaling of small-area PSCs to large-area solar modules to meet the demands of practical applications remains a significant challenge.The scalable production of high-quality perovskite films by a simple,reproducible process is crucial for resolving this issue.Furthermore,the crystallization behavior in the solution-processed fabrication of perovskite films can be strongly influenced by the physicochemical properties of the precursor inks,which are significantly affected by the employed solvents and their interactions with the solutes.Thus,a comprehensive understanding of solvent engineering for fabricating perovskite films over large areas is urgently required.In this paper,we first analyze the role of solvents in the solution-processed fabrication of large-area perovskite films based on the classical crystal nucleation and growth mechanism.Recent efforts in solvent engineering to improve the quality of perovskite films for solar modules are discussed.Finally,the basic principles and future challenges of solvent system design for scalable fabrication of high-quality perovskite films for efficient solar modules are proposed.

Multifunctional Perovskite Photodetectors: From Molecular-Scale Crystal Structure Design to Micro/Nano-scale Morphology Manipulation

Multifunctional photodetectors boost the development of traditional optical communication technology and emerging artificial intelligence fields, such as robotics and autonomous driving. However, the current implementation of multifunctional detectors is based on the physical combination of optical lenses, gratings, and multiple photodetectors, the large size and its complex structure hinder the miniaturization, lightweight, and integration of devices. In contrast, perovskite materials have achieved remarkable progress in the field of multifunctional photodetectors due to their diverse crystal structures, simple morphology manipulation, and excellent optoelectronic properties. In this review, we first overview the crystal structures and morphology manipulation techniques of perovskite materials and then summarize the working mechanism and performance parameters of multifunctional photodetectors. Furthermore, the fabrication strategies of multifunctional perovskite photodetectors and their advancements are highlighted, including polarized light detection, spectral detection, angle-sensing detection, and selfpowered detection. Finally, the existing problems of multifunctional detectors and the perspectives of their future development are presented.

The Main Progress of Perovskite Solar Cells in 2020-2021

Perovskite solar cells(PSCs)emerging as a promising photovoltaic technology with high efficiency and low manufacturing cost have attracted the attention from all over the world.Both the efficiency and stability of PSCs have increased steadily in recent years,and the research on reducing lead leakage and developing eco-friendly lead-free perovskites pushes forward the commercialization of PSCs step by step.This review summarizes the main progress of PSCs in 2020 and 2021 from the aspects of efficiency,stability,perovskite-based tandem devices,and lead-free PSCs.Moreover,a brief discussion on the development of PSC modules and its challenges toward practical application is provided.

Discrimination of dislocations in 4H-SiC by inclination angles of molten-alkali etched pits

Discrimination of dislocations is critical to the statistics of dislocation densities in 4H silicon carbide(4H-SiC),which are routinely used to evaluate the quality of 4H-SiC single crystals and homoepitaxial layers.In this work,we show that the inclination angles of the etch pits of molten-alkali etched 4H-SiC can be adopted to discriminate threading screw dislocations(TSDs),threading edge dislocations(TEDs)and basal plane dislocations(BPDs)in 4H-SiC.In n-type 4H-SiC,the inclination angles of the etch pits of TSDs,TEDs and BPDs in molten-alkali etched 4H-SiC are in the ranges of 27°−35°,8°−15°and 2°−4°,respectively.In semi-insulating 4H-SiC,the inclination angles of the etch pits of TSDs and TEDs are in the ranges of 31°−34°and 21°−24°,respectively.The inclination angles of dislocation-related etch pits are independent of the etching duration,which facilitates the discrimination and statistic of dislocations in 4H-SiC.More significantly,the inclination angle of a threading mixed dislocations(TMDs)is found to consist of characteristic angles of both TEDs and TSDs.This enables to distinguish TMDs from TSDs in 4H-SiC.

Identification of subsurface damage of 4H-SiC wafers by combining photo-chemical etching and molten-alkali etching

In this work,we propose to reveal the subsurface damage(SSD)of 4H-SiC wafers by photo-chemical etching and identify the nature of SSD by molten-alkali etching.Under UV illumination,SSD acts as a photoluminescence-black defect.The selective photo-chemical etching reveals SSD as the ridge-like defect.It is found that the ridge-like SSD is still crystalline 4H-SiC with lattice distortion.The molten-KOH etching of the 4H-SiC wafer with ridge-like SSD transforms the ridge-like SSD into groove lines,which are typical features of scratches.This means that the underlying scratches under mechanical stress give rise to the formation of SSD in 4H-SiC wafers.SSD is incorporated into 4H-SiC wafers during the lapping,rather than the chemical mechanical polishing(CMP).

Assessing the effect of hydrogen on the electronic properties of 4H-SiC

As a common impurity in 4 H silicon carbide(4 H-Si C),hydrogen(H)may play a role in tuning the electronic properties of 4 H-Si C.In this work,we systemically explore the effect of H on the electronic properties of both n-type and p-type4 H-Si C.The passivation of H on intrinsic defects such as carbon vacancies(V_(Si) )and silicon vacancies(V_(Si)) in 4 H-Si C is also evaluated.We find that interstitial H at the bonding center of the Si-C bond(H_(i)^(bc)) and interstitial H at the tetrahedral center of Si(H_(i)^(bc)) dominate the defect configurations of H in p-type and n-type 4 H-Si C,respectively.In n-type 4 H-Si C,the compensation of HSi-te iis found to pin the Fermi energy and hinder the increase of the electron concentration for highly N-doped 4 H-Si C.The compensation of Hbc iis negligible compared to that of V_(Si)on the p-type doping of Al-doped 4 H-Si C.We further examine whether H can passivate VCand improve the carrier lifetime in 4 H-Si C.It turns out that nonequilibrium passivation of VCby H is effective to eliminate the defect states of V_(Si),which enhances the carrier lifetime of moderately doped 4 H-Si C.Regarding the quantum-qubit applications of 4 H-Si C,we find that H can readily passivate V_(Si)during the creation of V_(Si)centers.Thermal annealing is needed to decompose the resulting V_(Si)-n H(n=1-4)complexes and promote the uniformity of the photoluminescence of V_(Si)arrays in 4 H-Si C.The current work may inspire the impurity engineering of H in 4 H-Si C.

Hyperdoped silicon:Processing,properties,and devices

Hyperdoping that introduces impurities with concentrations exceeding their equilibrium solubility has been attract-ing great interest since the tuning of semiconductor properties increasingly relies on extreme measures.In this review we fo-cus on hyperdoped silicon(Si)by introducing methods used for the hyperdoping of Si such as ion implantation and laser dop-ing,discussing the electrical and optical properties of hyperdoped bulk Si,Si nanocrystals,Si nanowires and Si films,and present-ing the use of hyperdoped Si for devices like infrared photodetectors and solar cells.The perspectives of the development of hy-perdoped Si are also provided.

Theoretical study on the improvement of the doping efficiency of Al in 4H-SiC by co-doping group-IVB elements

The p-type doping efficiency of 4 H silicon carbide(4 H-SiC)is rather low due to the large ionization energies of p-type dopants.Such an issue impedes the exploration of the full advantage of 4 H-SiC for semiconductor devices.In this study,we show that co-doping group-IVB elements effectively decreases the ionization energy of the most widely used p-type dopant,i.e.,aluminum(Al),through the defect-level repulsion between the energy levels of group-IVB elements and that of Al in 4 H-SiC.Among group-IVB elements Ti has the most prominent effectiveness.Ti decreases the ionization energy of Al by nearly 50%,leading to a value as low as~0.13 eV.As a result,the ionization rate of Al with Ti co-doping is up to~5 times larger than that without co-doping at room temperature when the doping concentration is up to 10^(18)cm^(-3).This work may encourage the experimental co-doping of group-IVB elements such as Ti and Al to significantly improve the p-type doping efficiency of 4 H-SiC.

Heterogeneous FASnI3 Absorber with Enhanced Electric Field for High-Performance Lead-Free Perovskite Solar Cells

Lead-free tin perovskite solar cells(PSCs)have undergone rapid development in recent years and are regarded as a promising ecofriendly photovoltaic technology.However,a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking.In the present study,a formamidinium tin iodide(FASnI;)perovskite absorber with a vertical Sn;gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites.Depth-dependent X-ray photoelectron spectroscopy revealed that the Fermi level upshifts with an increase in Sn;content from the bottom to the top in this heterogeneous FASnI;film,which generates an additional electric field to prevent the trapping of photo-induced electrons and holes.Consequently,the Sn;-gradient FASnI;absorber exhibits a promising efficiency of 13.82%for inverted tin PSCs with an open-circuit voltage increase of 130 mV,and the optimized cell maintains over 13%efficiency after continuous operation under 1-sun illumination for 1,000 h.

Unveiling the surface-interface properties of perovskite crystals and pivotal regulation strategies

Metal-halide perovskite solar cells have garnered significant research attention in the last decade due to their exceptional photovoltaic performance and potential for commercialization.Despite achieving remarkable power conversion efficiency of up to 26.1%,a substantial discrepancy persists when compared to the theoretical Shockley-Queisser(SQ)limit.One of the most serious challenges facing perovskite solar cells is the energy loss incurred during photovoltaic conversion,which affects the SQ limits and stability of the device.More significant than the energy loss occurring in the bulk phase of the perovskite is the energy loss occurring at the surface-interface.Here,we provide a systematic overview of the physical and chemical properties of the surface-interface.Firstly,we delve into the underlying mechanism causing the energy deficit and structural degradation at the surface-interface,aiming to enhance the understanding of carrier transport processes and structural chemical reactivity.Furthermore,we systematically summarized the primary modulating pathways,including surface reconstruction,dimensional construction,and electric-field regulation.Finally,we propose directions for future research to advance the efficiency of perovskite solar cells towards the radiative limit and their widespread commercial application.

Structure-regulated fluorine-containing additives to improve the performance of perovskite solar cells

Perovskite solar cells(PSCs)have seen remarkable progress in recent years,largely attributed to various additives that enhance both efficiency and stability.Among these,fluorine-containing additives have garnered significant interest because of their unique hydrophobic properties,effective defect passivation,and regulation capability on the crystallization process.However,a targeted structural approach to design such additives is necessary to further enhance the performance of PSCs.Here,fluoroalkyl ethylene with different fluoroalkyl chain lengths(CH_(2)CH(CF_(2))nCF_(3),n=3,5,and 7)as liquid additives is used to investigate influences of fluoroalkyl chain lengths on crystallization regulation and defect passivation.The findings indicate that optimizing the quantity of F groups plays a crucial role in regulating the electron cloud distribution within the additive molecules.This optimization fosters strong hydrogen bonds and coordination effects with FA+and uncoordinated Pb^(2+),ultimately enhancing crystal quality and device performance.Notably,1H,1H,2H-perfluoro-1-hexene(PF_(3))with the optimal number of F presents the most effective modulation effect.A PSC utilizing PF_(3)achieves an efficiency of 24.05%,and exhibits exceptional stability against humidity and thermal fluctuations.This work sheds light on the importance of tailored structure designs in additives for achieving high-performance PSCs.

Advances in Intermediates for the Solution-Processing of Perovskite Films

Owing to its superior efficiency and low cost,the solution-processable perovskite has rapidly become the latest favorite material in the field of photovoltaics.Although solution processing significantly reduces the threshold and cost of perovskite solar cells,the intricate composition and nonequilibrium nucleation of the perovskite precursor can result in leaky film.The precise control of perovskite nucleation and orientation is a fundamental prerequisite for achieving high-quality perovskite photoactive layers.In this process,the intermediate species that widely exists either in the precursor or the asprepared film acts as a transitional state for perovskite nucleation and growth from solution to solid,presenting an opportunity for controlling perovskite crystallization.Herein,we present an overview of the advancements in intermediates for solution-processing perovskite films to gain insights into the growth and manipulation of polycrystalline perovskite films.

Bioinspired molecules design for bilateral synergistic passivation in buried interfaces of planar perovskite solar cells

Trap-mediated energy loss in the buried interface with non-exposed feature constitutes one of the serious challenges for achieving high-performance perovskite solar cells(PSCs).Inspired by the adhesion mechanism of mussels,herein,three catechol derivatives with functional Lewis base groups,namely 3,4-Dihydroxyphenylalanine(DOPA),3,4-Dihydroxyphenethylamine(DA)and 3-(3,4-Dihydroxyphenyl)propionic acid(DPPA),were strategically designed.These molecules as interfacial linkers are incorporated into the buried interface between perovskite and SnO_(2) surface,achieving bilateral synergetic passivation effect.The crosslinking can produce secondary bonding with the undercoordinated Pb^(2+) and Sn^(4+) defects.The PSCs treated with DOPA exhibited the best performance and operational stability.Upon the DOPA passivation,a stabilized power conversion efficiency(PCE)of 21.5%was demonstrated for the planar PSCs.After 55 days of room-temperature storage,the unencapsulated devices with the DOPA crosslinker could still maintain 85%of their initial performance in air under relative humidity of-15%.This work opens up a new strategy for passivating the buried interfaces of perovskite photovoltaics and also provides important insights into designing defect passivation agents for other perovskite optoelectronic devices,such as light-emitting diodes,photodetectors,and lasers.

A shape memory scaffold for body temperature self-repairing wearable perovskite solar cells with efficiency exceeding 21%

Grain boundary cracks in flexible perovskite films can be repaired by filling with self-repairing polymers during the preparation and wearable operation.However,the self-repairing polymers are commonly active through external heating or humidification treatments,which cannot match with the human body's temperature tolerance of wearable devices.Herein,a body temperature-responsive shape memory polyurethane(SMPU)is demonstrated to achieve the real-time mechanical self-repairing of grain boundary cracks(~37°C).Furthermore,the strong intermolecular interaction between SMPU and the uncoordinated Pb2+and I−,can reduce the trap density in perovskite films.The blade-coated device achieves a power conversion efficiency(PCE)of 21.33%,which is among the best reported flexible perovskite solar cells(PSCs;0.10 cm2).Importantly,the device with SMPU can recover more than 80%of the PCE after 6000 cycles(bending radius:8 mm).Finally,the flexible PSCs are used for wearable solar power supply of a smartphone,which show great potential for self-repairing wearable electronics.

Controllable printing of large-scale compact perovskite films for flexible photodetectors

Perovskite materials are promising candidates for the next generation of wearable optoelectronics.However,due to uncontrolled crystallization and the natural brittle property of crystals,it remains a great challenge to fabricate large-scale compact and tough perovskite film.Here we report a facile method to print large-scale perovskite films with high quality for flexible photodetectors.By introducing a soluble polyethylene oxide(PEO)layer during the inkjet printing process,the nucleation and crystal growth of perovskite is well controlled.Perovskite films can be easily printed in large scale and patterned in high resolution.Moreover,this method can be extended to various kinds of perovskite materials,such as MAPbb(MA=methylammonium),MA_(3)Sb_(2)l_(9),and(BA)_(2)PbBr_(4)(BA=benzylammonium).The printed perovskite films show high quality and excellent mechanical performance.The photodetectors based on the MAPbBr3 perovskite films show a responsivity up to -1,036 mAA/V and maintain over 96.8%of the initial photocurrent after 15,000 consecutive bending cycles.This strategy provides a facile approach to prepare large-scale flexible perovskite films.It opens up new opportunities for the fabrication of diverse wearable optoelectronic devices.

Droplet Manipulation and Crystallization Regulation in Inkjet-Printed Perovskite Film Formation

Emerging organic–inorganic metal halide perovskite materials have become the focus of the optoelectronics research community owing to their excellent photoelectric properties.Nevertheless,challenges still exist for transferring the lab-made devices to largearea industrial modules.Inkjet printing(IJP)technology provides a promising way to fill the gap because of its precise droplet control and uniform large-scale deposition functions.Hence,an in-depth understanding of inkjet-printed perovskite films in terms of droplet manipulation and crystallization regulation is critical for upscaling the perovskite devices to commercial usage.In this review,we give an overview of inkjet-printed high-quality perovskite films and provide guidelines on inkjet-printing large-scale highperformance perovskite devices.First,we analyze theories of droplet formation and perovskite nucleation/crystallization dynamics and then focus on summarizing the perovskite film-formation strategies via IJP,in the aspects of ink engineering,the printing process,and posttreatment.Furthermore,we review the recent advances of inkjet-printed perovskite films on optoelectronic devices,such as perovskite solar cells,perovskite light-emitting diodes,and perovskite photodetectors.Finally,we highlight the“Trilogy Strategies,”including ink engineering,printing process,and posttreatment for printing high-quality perovskite films.

A general method for growth of perovskite single-crystal arrays for high performance photodetectors

Perovskite single-crystal arrays have attracted intensive attention because of their great potentials for integrated optoelectronic devices.However,the traditional top-down lithography strategy requires complex processing and is detrimental to perovskite crystal structures,which is incompatible to directly pattern perovskite single crystals.Herein,we report a lithography-free method to realize the controllable growth of perovskite single-crystal arrays.Through introducing a printed hydrophilic-hydrophobic substrate into the crystallization system,the MAPbCl_(3) single-crystal arrays with precise location and uniform size are effectively fabricated.This method can be applied to prepare diverse perovskite single-crystal arrays,including MAPbBr_(3),CsPbCl_(3),CsPbBr_(3),Cs_(3)Cu_(2)I_(5),Cs_(3)Bi_(2)I_(9),and(BA)_(2)(MA)_(3)Pb_(4)I_(11).The perovskite single crystals can be selectively grown on the electrodes to fabricate ultraviolet photodetectors.The strategy demonstrates a facile approach to fabricate large-scale perovskite single-crystal arrays and opens a pathway to produce diverse perovskite optoelectronic devices.