Solar Cell Materials Research Articles

Comparing the Efficacies of Electrospun ZnO and TiO2 Nanofibrous Interlayers for Electron Transport in Perovskite Solar Cells

ZnO and TiO2 are both well-known electron transport materials. Their comparison of performance is considered advantageous and novel. Therefore, a viable electrospinning route was considered for the development of highly polycrystalline TiO2 and ZnO nanofibers as an electron transport material (ETM) for perovskite solar cells. The materials were well-characterized in terms of different analytical techniques. The X-ray diffraction detected polycrystalline structural properties corresponding to TiO2 and ZnO. Morphological analysis by scanning electron microscopy revealed that the nanofibers are long, uniform, and polycrystalline, having a diameter in the nanometer range. Optoelectronic properties showed that TiO2 and ZnO exhibit absorption values in the ultraviolet and visible ranges, and band gap values for TiO2 and ZnO were 3.3 and 3.2 eV, respectively. TiO2 bandgap and semiconductor nature were more compatible with Electron Transport Layer (ETL) compared to ZnO. Electrical studies revealed that TiO2 nanofibers have enhanced values of conductivity and sheet carrier mobility compared to ZnO nanofibers. Therefore, higher photovoltaic conversion efficiency was achieved for TiO2 nanofibers (10.4%) compared to ZnO (8.5%).

Decreasing Carrier Mobility under Concentrated Illumination and Its Effect on the Series Resistance and Conversion Efficiency of Silicon Concentrator Solar Cells

The carrier mobility of solar cell materials is a critical physical parameter that determines the series resistance. Furthermore, series resistance is an essential factor affecting the conversion efficiency of concentrator solar cells under high sunlight illumination. However, there has been slight discussion regarding the relationship between these factors. In the previous study, it was reported that concentrated illumination decreased carrier mobility; however, the scattering mechanism has not yet been clarified. Moreover, carrier–carrier scattering was discussed; however, it did not cause a mobility reduction. Thus effective mass changes are discussed as a possible cause of the decrease in carrier mobility under concentrated illumination. The cause of the decrease in mobility under concentrated sunlight illumination cannot be fully elucidated; however, it is a change in lattice scattering. Furthermore, the effect of the decrease in mobility due to concentrated illumination on the series resistance and conversion efficiency of Si solar cells using numerical calculations is clarified. The increase in the series resistance caused by the mobility reduction is ≈10% under 30 suns.

Unveiling the Monoclinic Phase in CsPbBr3-xClx Perovskite Crystals, Phase Transition Suppression and High Energy Resolution γ-Ray Detection.

All-inorganic CsPbBr3 and CsPbCl3 perovskites are promising materials for high-performance solar cells and advanced radiation detection technologies with high stability. Here we report that CsPbBr3-xClx (x = 0-3) crystals exhibit eutectoid behavior for the melting points and phase transition temperatures. The well-known halide perovskite cubic phase transition temperature shifts near room temperature (∼37 °C for CsPbBr2Cl). We conducted an extensive crystallographic analysis on single crystals of 7 different compositions, including the end members CsPbBr3 and CsPbCl3. Contrary to previous beliefs, we discovered they exhibit a monoclinic structure with space group symmetry P21/m at room temperature, rather than the orthorhombic Pnma. This new structural model is more precise and features a unit cell volume that is four times larger than that of the orthorhombic model. From high-quality single crystals of CsPbBr2Cl, grown by the Bridgman method, we constructed γ-ray detectors achieving an energy resolution of 7.2% at 200 V for 57Co radiation. Thermally stimulated current spectroscopy of the CsPbBr2Cl samples revealed that the defect densities in crystals from different regions of the ingot were relatively uniform, with values of ∼4.72 × 1012 and ∼5.09 × 1012 cm-3. These findings indicate that low deep-level defect densities can be achieved that are consistent with the notable performance of the CsPbBr2Cl perovskite as a high-energy γ radiation detector.

Progress in MXenes and Their Composites as Electrode Materials for Electrochemical Sensing and Dye-Sensitized Solar Cells

In the present mini-review article, we have compiled the previously reported literature on the fabrication of MXenes and their hybrid composite materials based electrochemical sensors for the determination of phenolic compounds and counter electrodes for platinum (Pt)-free dye-sensitized solar cells (DSSCs). MXenes are two-dimensional (2D) materials with excellent optoelectronic and physicochemical properties. MXenes and their composite materials have been extensively used in the construction of electrochemical sensors and solar cell applications. In this paper, we have reviewed and compiled the progress in the construction of phenolic sensors based on MXenes and their composite materials. In addition, co1.unter electrodes based on MXenes and their composites have been reviewed for the development of Pt-free DSSCs. We believe that the present review article will be beneficial for the researchers working towards the development of phenolic sensors and DSSCs using MXenes and their composites as electrode materials.

Metastable Oxygen-Induced Light-Enhanced Doping in Mixed Sn-Pb Halide Perovskites.

Mixed Sn-Pb halide perovskites are promising absorber materials for solar cells due to the possibility of tuning the bandgap energy down to 1.2-1.3 eV. However, tin-containing perovskites are susceptible to oxidation affecting the optoelectronic properties. In this work, we investigated qualitatively and quantitatively metastable oxygen-induced doping in isolated ASnxPb1-xI3 (where A is methylammonium or a mixture of formamidinium and cesium) perovskite thin films by means of microwave conductivity, structural and optical characterization techniques. We observe that longer oxygen exposure times lead to progressively higher dark conductivities, which slowly decay back to their original levels over days. Here oxygen acts as an electron acceptor, leading to tin oxidation from Sn2+ to Sn4+ and creation of free holes. The metastable oxygen-induced doping is enhanced by exposing the perovskite simultaneously to oxygen and light. Next, we show that doping not only leads to the reduction in the photoconductivity signal but also induces long-term effects even after loss of doping, which is thought to derive from consecutive oxidation reactions leading to the formation of defect states. On prolonged exposure to oxygen and light, optical and structural changes can be observed and related to the formation of SnOx and loss of iodide near the surface. Our work highlights that even a short-term exposure to oxygen immediately impairs the charge carrier dynamics of the perovskite, while structural perovskite degradation is only noticeable upon long-term exposure and accumulation of oxidation products. Hence, for efficient solar cells, exposure of mixed Sn-Pb perovskites to oxygen during production and operation should be rigorously blocked.

Machine learning assisted designing of hole-transporting materials for high performance perovskite solar cells

In recent years, the advancement of perovskite solar cells has accelerated, leading to continuous performance improvements. Over the past few years, machine learning (ML) has gained popularity among scientists researching perovskite solar cells. In this study, ML is used to screen hole-transporting materials for perovskite solar cells. To construct machine-learning (ML) models, data from prior investigations are collected. Out of four machine learning algorithms trained for predicting reorganization energy (Rh), the gradient boosting regression model stood out as the most effective, attaining an R2 value of 0.89. Data visualization analysis is then utilized to scrutinize the patterns within the dataset. 10,000 new compounds are generated. Chemical space of generated compounds is visualized using various measures. Minor structural modifications resulted in only a slight alteration in reorganization energy (Rh). The newly introduced multidimensional framework has the potential to efficiently screen materials in a short amount of time.

Molecular engineering of oxadiazole-based small organic-functional molecules as hole transporting materials for dopant-free perovskite solar cells

The present investigation concerns the synthesis and characterization of new hole-transporting materials (HTMs) for dopant free perovskite solar cells (PSCs). In this work, emphasis is placed on three new HTMs, specifically materials P-H, P-OMe, and P-CN, whose center-core is 2,2'-(4,8-bis(octyloxy)benzo[1,2-b:4,5-b']dithiophene (OBDT) and combined with two donor units of substituted triphenylamine as at both ends along with oxadiazole acceptor units in between donor and OBDT. The fabrication of perovskite solar cell devices using new HTMs and compared the power conversion performance with the standard spiro-OMeTAD HTM. Several spectroscopic techniques were utilized to characterize the properties of the new HTMs, such as FESEM analysis of thin-film morphologies, time-dependent photoluminescence (PL) spectra, and mobility measurements. The HTMs P-OMe established a compressed and steady protective layer on the perovskite layer. This layer contributed to the development of open-circuit voltage (VOC) and short-circuit current density (JSC), both of which are crucial for accomplishing high power conversion efficiency (PCE) in PSCs. The PSC device integrating the P-OMe HTM displayed a superior PCE of 21.14 % over an active area of 0.22 cm2. This activity was related to the standard device that utilized the standard Spiro-OMeTAD HTM, which accomplished a PCE of 17.46 %. The improved devices with the P-OMe HTM continued about 90 % of their initial PCE throughout maximum power point tracking (MPPT) for 90 days. Furthermore, these devices engaged in their activity over a further 2160 h under various temperature settings (25 °C and 35 °C), probably because of the hydrophobic property of the HTM.

Enhancing hole-transport efficiency in (CH3NH3)2CuClxBr4-x perovskite solar cells through functionalization of multi-walled carbon nanotubes

This study addresses the conductivity limitation of conventional hole-transporting layers (HTLs) like Spiro-OMeTAD in perovskite solar cells. We integrate functionalized multi-walled carbon nanotubes (MWCNTs) into Spiro-OMeTAD and examine the impact of chemical oxidation/functionalization of MWCNTs on their application in perovskite solar cells. Various ratios of H2SO4/HNO3 mixture were employed to functionalize MWCNTs, with FTIR analysis confirming functional group attachments on the nanotube walls. Raman spectroscopy was utilized to analyze defect formation in the MWCNTs, while FESEM images displayed both the tubular structure and morphological alterations resulting from functionalization. XRD analysis was conducted to examine the structural variances resulting from different functionalization ratios. A lead-free copper-based perovskite (CH3NH3)2CuBr4-xClx (x = 0.5), synthesized via a straightforward solution method, served as the active material for solar cells. The XRD assessment of the active material confirmed perovskite formation, with morphological analysis revealing a layered structure. Diffuse Reflectance Spectroscopy (DRS) measurements yielded a bandgap of approximately 1.86 eV for the perovskite. Dark I–V measurements were executed for Spiro-OMeTAD films incorporated with pure and functionalized MWCNTs, showcasing improved conductivity attributed to charge carrier conduction via defect passivation. Hybrid solar cells were fabricated with structures such as TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/Spiro-OMeTAD/Ag, and TiO2/(CH3NH3)2CuBr4-xClx (x = 0.5)/functionalized MWCNTs/Spiro-OMeTAD/Ag. These cells demonstrated enhanced stability, retaining over 65 % of their initial efficiency after 10 days of storage, attributed to improved moisture permeability inferred from contact angle measurements and XRD analysis. Photovoltaic characterization revealed significant improvements in fill factor (∼70 %), short-circuit current density (2.94 mA), open-circuit voltage (0.70 V), and power conversion efficiency (PCE) (1.6 %) for the FTO/TiO2/(CH3NH3)2CuCl0·5Br3.5/Spiro-MWCNT-1/Ag device.

Preparation of efficient all-inorganic perovskite solar cells from large grain via 1-heptanamine stabilised CsPbI2Br nanoparticles with NH4SCN additive

CsPbI2Br is a potential material for perovskite solar cells (PSCs) due to its better thermal stability and high efficiency. Centrifugal deposition for film formation greatly simplifies the steps of the conventional anti-solvent spin coating method, but there are still problems hindering progress, such as small grain size and poor photoelectric performance. In this work, NH4SCN was introduced as an additive during the preparation of heptylamine (C7H17N) stabilised CsPbI2Br nanoparticles (NCs) and the films were prepared by centrifugal deposition. The results show that the low melting temperature compounds which formed by thiourea from NH4SCN decomposition during annealing and unreacted PbX2 would link the small grains together by melting and flowing; after PbX2 precipitation and reaction with CsX, the grain size was significantly increased by about 95 % compared to that of the untreated film. Due to large grains, less defects and high crystallinity, the final power conversion efficiency and fill factor reached 12.25 % and 0.70, respectively.

Enhancing Stability in All-Vacuum-Evaporated Hybrid Perovskite Solar Cells via a Bipolar Host as a Hole-Transporting Layer.

Growing an ultrathin hybrid organic-inorganic perovskite film while maintaining high efficiency and addressing photostability challenges for commercial devices remains a significant hurdle. In this study, we explore the incorporation of organometallic copper phthalocyanine (CuPc) and MS-OC (a previously published spiro-based interfacial material for perovskite solar cells (PSCs), featuring an ortho-oriented carbazole donor) as an addition to the hole-transporting layer (HTL) in all-vacuum-deposited Cs0.06FA0.94Pb(I0.68Br0.32)3 PSCs. By innovatively introducing a 3 nm-thin MS-OC layer at the CuPc-perovskite interface, we achieve a deeper understanding of the crystallographic dynamics of perovskites, resulting in a uniform and pinhole-free film. We demonstrate that PSCs utilizing the CuPc HTL with an MS-OC interfacial layer in a p-i-n architecture achieve a power conversion efficiency (PCE) of up to 14.42%. Remarkably, the CuPc/MS-OC-based device exhibits outstanding long-term photostability, maintaining its initial PCE over 400 h (T100 = 400 h) under continuous sunlight illumination. By configuring the device architecture as ITO/MoO3/CuPc/MS-OC/perovskite/C60/BCP/Ag, we find that the evaporated MS-OC thin films effectively reduce nonradiative losses, passivate the perovskite, and enhance device performance. Our findings indicate that the polarity of the underlying surface significantly influences perovskite nucleation, underscoring the potential to improve photostability by controlling interfacial imperfections.

Innovative Materials for High-Performance Tin-Based Perovskite Solar Cells: A Review

With the rapid development of lead-based perovskite solar cells, tin-based perovskite solar cells are emerging as a non-toxic alternative. Material engineering has been an effective approach for the fabrication of efficient perovskite solar cells. This paper summarizes the novel materials used in tin-based perovskite solar cells over the past few years and analyzes the roles of various materials in tin-based devices. It is found that self-assembling materials and fullerene derivatives have shown remarkable performance in tin-based perovskite solar cells. Finally, this article discusses design strategies for new materials, providing constructive suggestions for the development of innovative materials in the future.

Small Molecular Dibenzo[b,d]thiophene-Based Hole Transport Materials for Tin-Lead Perovskite Solar Cell.

The most commonly used hole transport material (HTM) in tin-lead (Sn-Pb) perovskite solar cells (PSCs) is the aqueous poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), and its inherent hygroscopic and acidic features greatly limit the power conversion efficiency (PCE) and stability of PSCs. Concerning this, by selecting dibenzo[b,d]thiophene 5,5-dioxide (DBTDO) as the core and engineering the donor units, 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (TPA) and N1-(4-(bis(4-methoxyphenyl)amino)phenyl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine (DTPA) as peripheral groups, two alternative HTMs are reported. Among them, the HTM TPA-DBTDO-DTPA can form a smoother film, which is conducive to the growth of dense perovskite film on it and shows the most suitable energy level. Meanwhile, the sulfonyl unit can passivate the buried defects of perovskite and improve the open-circuit voltage (VOC) of Sn-Pb mixed PSCs. Correspondingly, the TPA-DBTDO-DTPA-based PSC achieves a champion power conversion efficiency of 22.6% and maintains 75.9% of the initial PCE after aging 1000 h in a nitrogen (N2) environment, which fully outperforms the PEDOT:PSS-based control device.

Novel Structures for PV Solar Cells: Fabrication of Cu/Cu2S-MWCNTs 1D-Hybrid Nanocomposite

The production of cost-effective novel materials for PV solar cells with long-term stability, high energy conversion efficiency, enhanced photon absorption, and easy electron transport has stimulated great interest in the research community over the last decades. In the presented work, Cu/Cu2S-MWCNTs nanocomposites were produced and analyzed in the framework of potential applications for PV solar cells. Firstly, the surface of the produced one-dimensional Cu was covered by Cu2S nanoflake. XRD data prove the formation of both Cu and Cu2S structures. The length and diameter of the one-dimensional Cu wire were 5–15 µm and 80–200 nm, respectively. The thickness of the Cu2S nanoflake layer on the surface of the Cu was up to 100 nm. In addition, the Cu/Cu2S system was enriched with MWCNTs. MWCNs with a diameter of 50 nm interact by forming a conductive network around the Cu/Cu2S system and facilitate quick electron transport. Raman spectra also prove good interfacial coupling between the Cu/Cu2S system and MWCNTs, which is crucial for charge separation and electron transfer in PV solar cells. Furthermore, UV studies show that Cu/Cu2S-MWCNTs nanocomposites have a wide absorption band. Thus, MWCNTs, Cu, and Cu2S exhibit an intense absorption spectrum at 260 nm, 590 nm, and 972 nm, respectively. With a broad absorption band spanning the visible–infrared spectrum, the Cu/Cu2S-MWCNTs combination can significantly boost PV solar cells’ power conversion efficiency. Furthermore, UV research demonstrates that the plasmonic character of the material is altered fundamentally when CuS covers the Cu surface. Additionally, MWCN-Cu/Cu2S nanocomposite exhibits hybrid plasmonic phenomena. The bandgap of Cu/Cu2S NWs was found to be approximately 1.3 eV. Regarding electron transfer and electromagnetic radiation absorption, the collective oscillations in plasmonic metal-p-type semiconductor–conductor MWCNT contacts can thus greatly increase energy conversion efficiency. The Cu/Cu2S-MWCNTs nanocomposite is therefore a promising new material for PV solar cell application.

Probing into the low efficiency of CdS/SnS-based solar cells and remediation through surface treatments

Tin sulfide (SnS) is a highly promising photovoltaic absorption material in thin-film solar cells with abundant reserves, environmental friendliness, low cost and long-term stability. An efficiency of up to 4.8 % has been achieved for SnS absorber/CdS heterojunction solar cells where the CdS buffer layer is usually obtained by chemical bath deposition. However, current CdS/SnS devices often suffer from severe interface recombination loss, which deteriorates device performance. This report focuses on the CdS film surface to identify performance-degrading factors for CdS/SnS-based solar cells. XRD and XPS reveal numerous oxides on freshly fabricated CdS films increasing surface roughness and reducing conductivity. Herein, a method based on ammonium sulfide (AS) chemical treatment is proposed, which can effectively reduce the oxide content on the surface of CdS and optimize the band alignment, leading to the facilitation of charge carrier transport and the suppression of interface recombination. Consequently, the PCE of the FTO/CdS/SnS/Ag device is enhanced about three times (from 0.18 % to 0.47 %) with excellent moisture stability.

A Pyrrole Modified 3,4-Propylenedioxythiophene Conjugated Polymer as Hole Transport Layer for Efficient and Stable Perovskite Solar Cells.

Despite the outstanding electric properties and cost-effectiveness of poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives, their performance as hole transport layer (HTL) materials in conventional perovskite solar cells (PSCs) has lagged behind that of widely used spirobifluorene-based molecules or poly(triaryl amine). This gap is mainly from their poor solubility and energy alignment mismatch. In this work, the design and synthesis of a pyrrole-modified HTL (PPr) based on 3,4-propylenedioxythiophene (ProDOT) are presented for efficient and stable PSCs. As a result of the superior defects passivation ability, excellent contact with perovskite, enhanced hole extraction, and high hydrophobicity, the unencapsulated PPr-based PSCs showed the peak PCE of 21.49% and outstanding moisture stability (over 4000 h). This work highlights the potential application of ProDOT-based materials as HTL for PSCs and underscores the importance of the rational design of PEDOT and its derivatives.

Black Jamun Fruit Peel Extract Modified Gum Acacia Biopolymer Suitable for Energy Device Applications via Charge Transfer Enhancement

The visible light absorption capabilities, along with its electrical characteristics, of a low-cost, plant-based, biopolymer, gum acacia, have been chemically modified by tailoring its defect concentrations via pH modification, where the acid solvent of fruit (peel) extracts of jamun was used to influence the chemical structure by reactive modification. Ultraviolet-visible and photoluminescence spectroscopy of the gum acacia biopolymer treated with the extracted anthocyanin from jamun peel showed a prominent, characteristic red shift in the visible spectrum range. Impedance spectroscopy analysis showed the occurrence of localized ionic conduction. The bulk conductivity of the modified specimens increased due to the profound release of conducting ions in the water-swollen network. The reactively modified biopolymer could be used in multiple fields of material science, specifically in energy device applications, viz., photovoltaics (PV), by utilizing its cost effectiveness and photolytic effectiveness. 2nd, as a polymer electrolyte and dye-sensitised solar cells (DSSCs) material by utilizing its capacity of gel formation. In our research described in this article, the underlying charge transfer mechanism for such responses was examined after crosslinking in the organic dyes extracted from the peel of jamun fruit with gum acacia.

CALCULATION OF ELECTRONIC PROPERTIES OF LiBX3 (B = Pb AND Sn; X = Br, Cl AND I) CUBIC PHASE BY DENSITY FUNCTIONAL THEORY

Perovskite solar cells utilize perovskite as the active material to convert sunlight into electrical energy. Perovskite is a compound with a crystal structure of ABX₃, where A and B are cations, and X is an anion, usually a halide. Research continues to find perovskites with high efficiency. This efficiency is related to the electronic structure, which can be analyzed using Density Functional Theory (DFT). In this study, the electronic structure of cubic phase LiBX₃ perovskites (B = Pb and Sn; X = Br, Cl, and I) is investigated using Quantum ESPRESSO software. Various parameters such as cut-off energy, k-points, and lattice constants were modified to obtain optimal values. From the optimization results, the band gap, DOS, and PDOS values for the six perovskites were obtained. The resulting band gap energy (Eg) are LiPbBr₃ at 1,71 eV, LiPbCl₃ at 1,87 eV, LiPbI₃ at 1,43 eV, LiSnBr₃ at 0,51 eV, LiSnCl₃ at 0,65 eV, and LiSnI₃ at 0,28 eV. These results show that the band gap energy values increase with the change in atomic radius from Sn to Pb and decrease with the change in atomic radius from Cl, Br to I. The electronic structure calculations of LiBX₃ (B = Pb and Sn; X = Br, Cl, and I) show semiconductor properties that have the potential to be used as light-absorbing materials in perovskite solar cells. This study states that LiBX₃ has great potential in solar cell applications and offers a deep understanding of the relationship between crystal structure and its electronic properties.

Trends Research Characterization of TiO2 Thin Films as Solar Cell Materials (2015-2024): A Systematic Review

Research in the field of solar cells continues to increase along with the development of the times and human needs for renewable energy sources. One of the fields of study that is often used as a research topic is the development of Thin Film Solar Cells or known as Thin Film Solar Cells (TFSC). This research aims to identify and analyze research trends of synthesis of Ti02 thin films as solar cell materials. This research method is descriptive and analytical. The data used in this research was obtained from documents indexed by Google Scholar from 2015-2024 using Publish or Perish and Dimension.ai. Research procedures use PRISMA guidelines. The data identified and analyzed are the type of publication, publication source, and the title of research on synthesis of Ti02 thin films as solar cell materials that is widely cited. The data analysis method uses bibliometric analysis assisted by VOS viewer software. The results of the analysis show that research trend on synthesis of TiO2 thin films as solar cell materials indexed by Google Scholar from 2015 to 2024 has experienced increases and decreases. There are many documents in the form of articles, proceedings, chapters, preprints, monograph and edited books that discuss research about synthesis of Ti02 thin films as solar cell materials. Key words that are often used in research about it are dye sensitized cell, electrode, electron, characterization, etc.

Rapid Thermal-Driven Crystal Growth and Defect Suppression in Antimony Selenide Thin Film for Efficient Solar Cells.

Antimony selenide (Sb2Se3) has demonstrated considerable potential and advancement as a light-absorbing material for thin-film solar cells owing to its exceptional optoelectronic characteristics. However, challenges persist in the crystal growth, particularly regarding the nucleation mechanism during pre-selenization process for Sb2Se3. The defects originating from this process significantly impact the quality of the absorber layer, leading to the degradation in the power conversion efficiency (PCE) of the device. Herein, the evolution of pre-selenization using rapid thermal processing (RTP) on the crystallization quality of Sb2Se3 film is systematically investigated. By optimizing the initial nucleation process during pre-selenization, resulting in a reduction of grain boundaries and nucleation centers, the Sb2Se3 thin films demonstrate enhanced crystallinity and pinholes-free morphology. It is found that the improved quality of the grain interior and interfaces of the Sb2Se3 absorber can mitigate intrinsic defects within the bulk layer, and passivate interfacial defect recombination. As a result, the short circuit current density (JSC) is elevated to 28.97mA cm-2, and a competitive efficiency of 9.03% is achieved in Sb2Se3 device. This study provides comprehensive insight into the process of crystal growth and the mechanism for defect suppression, which holds guiding significance for advancing photovoltaic performance.

Surface Reaction Induced Compressive Strain for Stable Inorganic Perovskite Solar Cells

AbstractCesium‐based inorganic perovskites have emerged as promising light‐harvesting materials for perovskite solar cells (PSCs) due to their promising thermal‐ and photo‐stability. However, obstacles to commercialization remain regarding their phase instability. In this work, we report a facile and effective strategy to regulate the surface compressive strain via in situ surface reaction to stabilize CsPbI3 perovskite. The use of a chelating ligand with a molecular configuration closely matching the integer multiples of the unit cell lattice parameters of CsPbI3 induces compressive strain at the surface of CsPbI3. The chemical bonding and strain modulation synergistically not only passivate film defects, but also inhibit perovskite phase degradation, thus significantly improving the intrinsic stability of inorganic perovskite. Consequently, enhanced power conversion efficiency (PCE) of 21.0 % and 18.6 % were respectively achieved in 0.16‐cm2 lab‐scale devices and 25.3‐cm2 solar modules. Further, surface reaction enables PSCs with enhanced thermal and operational stability; these devices retain over 95 % of their initial PCE after damp‐heat tests (i.e., in 85 °C and 85 % R. H. air) for 2000 h, and remain 99 % of their initial PCE after operating for 2000 h, representing one of the most stable inorganic PSCs reported so far.