Search

Perovskite materials such as organic‐inorganic MAPbX3 (X = Cl, I, Br) have attracted broad interests in photoelectric applications, such as image sensors and photovoltaics. Here, a facile and general approach, called soft‐print solvent‐assisted evaporation crystallization (SSEC) is reported, for fabrication of highly crystallized, air‐stable, and flexible perovskite micromesh films, including organic–inorganic (MAPbX3) and inorganic (CsPbX3) perovskite. Scanning and transmission electron microscopy (SEM/TEM) characterization reveals their high crystallinity without obvious grain boundaries. The photodetectors constructed based on MAPbI3 micromesh films exhibit a typical responsivity of ≈352 A W−1 and detectivity of ≈5.7 × 1013 Jones (at 650 nm in wavelength). The MAPbI3 micromesh film also shows good mechanical stability when bended at different bending radius, and after 800 bending cycles, they still exhibit highly reproducible photocurrent and on/off switching ratios. Furthermore, they are also air‐stable that they can survive for >20 days in high humid environments (65–75%) with <10% reduction in photocurrent. This work provides a facile and scalable approach for fabrication of highly crystallized, stable, and flexible perovskite micromesh films for a variety of optoelectronic applications with improved performance and durability. [ABSTRACT FROM AUTHOR]

In this study, we employed the one-dimensional solar cell capacitance simulator (SCAPS-1D) software to optimize the performance of Pb-based and Sn-based (Pb-free) all-inorganic perovskites (AIPs) and organic–inorganic perovskites (OIPs) in perovskite solar cell (PSC) structures. Due to the higher stability of AIPs, the performance of PSCs incorporating Cs-based perovskites was compared with that of FA-based perovskites, which are more stable than their MA-based counterparts. The impact of AIPs such as CsPbCl3, CsPbBr3, CsPbI3, CsSnCl3, CsSnBr3, and CsSnI3, as well as including FAPbCl3, FAPbBr3, FAPbI3, FASnCl3, FASnBr3, and FASnI3, was investigated. SnO2 and Cu2O were selected as an inorganic electron transport layer (ETL) and a hole transport layer (HTL), respectively. CsSnBr₃, CsSnI₃, FASnCl₃, and FASnBr₃ exhibited higher efficiency compared to their Pb-based counterparts. Additionally, most Cs-based perovskites, excluding CsPbI₃, demonstrated better performance relative to their FA counterparts. CsSnI3 AIP device also shows the highest short circuit current density (JSC) of 32.85 mA/cm2, the best power conversion efficiency (PCE) of 16.00%, and the least recombination at the SnO2/CsSnI3 interface. The thickness, doping, and total defect density of CsSnI3 PSC have been systematically investigated and optimized to obtain the PCE of 17.36%. These findings highlight the potential of CsSnI3 PSCs as efficient and environmentally friendly PSCs. [ABSTRACT FROM AUTHOR]

Organic–inorganic perovskite (OIP) nanoparticles exhibit excellent luminescence properties and photovoltaic efficiency and can be used in bulk and thin films. In this study, a mechanically robust OIP quantum dot dispersion layer was deposited on glass substrates via a rapid synthesis process. First, hierarchical nanoporous structures with a thickness of 1.5 μm were formed on the glass surface. These structures were dipped in a precursor liquid and then dried. Thereafter, OIP crystals of methylammonium lead bromide (MAPbBr 3) with sizes of 5–10 nm were precipitated inside nanopores. The low-temperature luminescence properties of the obtained samples at 4–110 K were compared with those of spin-coated films and bulk MAPbBr 3. The emission peak wavelength of the sample precipitated in the nanopores on the glass surface (with an energy of 2.16 eV) was lower than that of the bulk sample (with an energy of 2.01 eV), and its luminescence intensity was two orders of magnitude higher than that of the bulk sample. The proposed method can be used to fabricate solar cells, electroluminescent devices, and scintillators. [ABSTRACT FROM AUTHOR]

We explore the crystal structure and luminescent properties of a new 1D organic–inorganic hybrid, MHy2SbI5, based on methylhydrazine. The compound reveals the red photoluminescence (PL) originating from the 5s2 electron pairs of Sb(III) as well as complex structural behavior. MHy2SbI5 crystalizes in two polymorphic forms (I and II) with distinct thermal properties and structural characteristics. Polymorph I adopts the acentric P212121 chiral space group confirmed by SHG, and, despite a thermally activated disorder of MHy, does not show any phase transitions, while polymorph II undergoes reversible low-temperature phase transition and high-temperature reconstructive transformation to polymorph I. The crystal structures of both forms consist of 1D perovskite zig-zag chains of corner-sharing SbI6 octahedra. The intriguing phase transition behavior of II is associated with the unstable arrangement of the [SbI5]2−∞ chains in the structure. The energy band gap (Eg) values, estimated based on the UV-Vis absorption spectra, indicate that both polymorphs have band gaps, with Eg values of 2.01 eV for polymorph I and 2.12 eV for polymorph II. [ABSTRACT FROM AUTHOR]

Organic-inorganic perovskites hold great promise as optoelectronic semiconductors for pure color light emitting and photovoltaic devices. However, challenges persist regarding their photostability and chemical stability, which limit their extensive applications. This paper investigates the laser radiation hardening and self-healing-induced properties of aged MAPbBr3 perovskites encapsulated in NiO nanotubes (MAPbBr3@NiO) using photoluminescence (PL) and fluorescence lifetime imaging (FLIM). After deliberately subjecting the MAPbBr3@ NiO to atmospheric conditions for two years, the sample remains remarkably stable. It exhibits no changes in PL wavelength during UV laser irradiation and self-healing. Furthermore, exposure to UV light at 375 nm enhances the PL of the self-healed MAPbBr3@NiO. FLIM analysis sheds light on the mechanism behind photodegradation, self-healing, and PL enhancement. The results indicate the involvement of many carrier-trapping states with low lifetime events and an increase in peak lifetime after self-healing. The formation of trapping states at the perovskite/nanotube interface is discussed and tested. This study provides new insights into the dynamics of photo-carriers during photodegradation and self-healing in organic-inorganic perovskites. [ABSTRACT FROM AUTHOR]

We explore the crystal structure and luminescent properties of a new 1D organic–inorganic hybrid, MHy2SbI5, based on methylhydrazine. The compound reveals the red photoluminescence (PL) originating from the 5s2 electron pairs of Sb(III) as well as complex structural behavior. MHy2SbI5 crystalizes in two polymorphic forms (I and II) with distinct thermal properties and structural characteristics. Polymorph I adopts the acentric P212121 chiral space group confirmed by SHG, and, despite a thermally activated disorder of MHy, does not show any phase transitions, while polymorph II undergoes reversible low-temperature phase transition and high-temperature reconstructive transformation to polymorph I. The crystal structures of both forms consist of 1D perovskite zig-zag chains of corner-sharing SbI6 octahedra. The intriguing phase transition behavior of II is associated with the unstable arrangement of the [SbI5]2−∞ chains in the structure. The energy band gap (Eg) values, estimated based on the UV-Vis absorption spectra, indicate that both polymorphs have band gaps, with Eg values of 2.01 eV for polymorph I and 2.12 eV for polymorph II.

Organic-inorganic perovskites hold great promise as optoelectronic semiconductors for pure color light emitting and photovoltaic devices. However, challenges persist regarding their photostability and chemical stability, which limit their extensive applications. This paper investigates the laser radiation hardening and self-healing-induced properties of aged MAPbBr3 perovskites encapsulated in NiO nanotubes (MAPbBr3@NiO) using photoluminescence (PL) and fluorescence lifetime imaging (FLIM). After deliberately subjecting the MAPbBr3@ NiO to atmospheric conditions for two years, the sample remains remarkably stable. It exhibits no changes in PL wavelength during UV laser irradiation and self-healing. Furthermore, exposure to UV light at 375 nm enhances the PL of the self-healed MAPbBr3@NiO. FLIM analysis sheds light on the mechanism behind photodegradation, self-healing, and PL enhancement. The results indicate the involvement of many carrier-trapping states with low lifetime events and an increase in peak lifetime after self-healing. The formation of trapping states at the perovskite/nanotube interface is discussed and tested. This study provides new insights into the dynamics of photo-carriers during photodegradation and self-healing in organic-inorganic perovskites.

Organic–inorganic hybrid perovskites (OHPs) with a rich reservoir of distinct physical attributes have been considered as promising resistive switching materials for next‐generation electronic devices, including resistive random‐access memory (RRAM) devices, artificial synapses, and logic operation. In this review, we first briefly introduce the structural and photoelectronic properties of OHPs materials, followed by elaborating the typical lateral/vertical device architectures and commonly‐used device fabrication technologies. Secondly, recent progress of OHPs in three categories of RRAM, artificial synapses, and logic operation, including various materials design, outstanding electrical behaviors, and multifunctional applications, are well discussed. Besides, the operational mechanisms and performance improvement strategies are summarized in a recapitulative way. Finally, current challenges and future development prospects of OHPs‐based devices are demonstrated to provide a better guideline for the next‐generation technical revolution. This review offers an encouraging recognition that OHPs hold immense expectation to keep up with the upcoming big‐data and artificial intelligence era. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites (OHPs) with a rich reservoir of distinct physical attributes have been considered as promising resistive switching materials for next‐generation electronic devices, including resistive random‐access memory (RRAM) devices, artificial synapses, and logic operation. In this review, we first briefly introduce the structural and photoelectronic properties of OHPs materials, followed by elaborating the typical lateral/vertical device architectures and commonly‐used device fabrication technologies. Secondly, recent progress of OHPs in three categories of RRAM, artificial synapses, and logic operation, including various materials design, outstanding electrical behaviors, and multifunctional applications, are well discussed. Besides, the operational mechanisms and performance improvement strategies are summarized in a recapitulative way. Finally, current challenges and future development prospects of OHPs‐based devices are demonstrated to provide a better guideline for the next‐generation technical revolution. This review offers an encouraging recognition that OHPs hold immense expectation to keep up with the upcoming big‐data and artificial intelligence era.

Abstract Thin film solar cell materials such as 3D metal halide perovskites are cheaper alternatives to silicon. Presently, the conversion efficiency of 3D lead halide perovskites is 25.5% (2021), which represents an increase of more than 550% since their discovery in 2009 (3.8%). Despite this remarkable progress, concerns about the toxicity of lead have sparked the quest for possible substitutes, in particular, 3D tin halide perovskites. This review covers the general properties of tin halide perovskites, synthesis and stability. It also identifies possible gaps and application beyond solar cells.

The perovskite and organic solar cells are becoming the most cognizant of the photovoltaic communities. The Spiro-OMeTAD organic hole transport layer (HTL) shows a significant impact on the CH 3 NH 3 SnI 3 perovskite solar cell (PSC) with TiO 2 as the electron transport layer (ETL). So, we optimized the physical and electrical parameters of the organic HTL. Electrical optimization shows that the power conversion efficiency (PCE) of the cell can reach up to 18.10 % for the electron affinity of the organic HTL material of about 2.5 e V . Further, the interpretation of the practical scale of series and shunt resistance reveals the maximum PCE of the cell as 13.30 % at 0.5 Ω c m 2 and 1 × 10 6 Ω c m 2 respectively. Also, the performance of the cell is analyzed for the hole mobility of the organic HTL material, which revealed the best PCE of the cell to 13.31 % . Moreover, the physical parameters are also optimized for the cell performance with illumination intensities which pointed out that the performance of the novel organic HTL perovskite solar cell is optimum for illumination intensity around 0.5 S u n (500Wm -2 ). Finally, the overall light harnessing efficiency or PCE of the proposed solar cell is declared to be 13.30 % , and the other performance parameters as open circuit voltage (V oc ), short circuit current (J sc ), and fill factor (FF) are 0.764 V , 25.86 m A c m - 2 and 67.29 % , respectively., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

[Display omitted] • A mixed dimensional catalyst based on FAPbBr 3 and 2D materials are prepared through directly synthesis. • The behavior of FAPbBr 3 in-situ growth on 2D materials are demonstrated. • The products can be controlled by engineering the growth of FAPbBr 3 on 2D materials. Constructing mixed dimensional materials have been regarded as an outstanding approach to maximum the advantages from materials of different dimensions. In this work, we prepared a mixed dimensional photocatalyst based on Formamidinium lead bromide (FAPbBr 3) perovskite and 2D materials (2DMs). The aim of this work is to utilize distributions of the active sites in 2DMs, through growing FAPbBr 3 on the different position of 2DMs, the concentration of photogenerated charges is manipulated, thus conducting different reactions. A pre-treatment using HBr to increase the unsaturated bonds in MoS 2 presents significant influence on the FAPbBr 3 growth and its photocatalytic product. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) confirm that the perovskite nanoparticles were well loaded on the 2D materials. The photocatalytic process and the heterojunction arrangement are demonstrated by X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence (TRPL), electron paramagnetic resonance (EPR) and surface photovoltage microscopy (SPVM). By adjusting the weight ratios and growth of FAPbBr 3 on the top of 2DMs, the optimized composite photocatalyst (with 30 wt% of FAPbBr 3) exhibits remarkable photoactivity for oxidation of benzyl alcohol into benzaldehyde (30 wt% FAPbBr 3 @WS 2 performed 75.9% conversion in 4 h, approximately 9-fold than the pure 2DMs). Meanwhile, by growing FAPbBr 3 on the edge of 2DMs, benzoic acid is obtained as the product. Although longer reaction time is needed, the photocatalyst performs outstanding activity (30 wt% FAPbBr 3 @MoS 2 reached 84.5% conversion in 5 h). [ABSTRACT FROM AUTHOR]

The influence of DMF and DMSO solvents on the properties of organic–inorganic perovskite films obtained at the ratio of starting reagents PbI2:CH3NH3I = 1:2 was studied. It was found that a dense film is formed from solutions in DMSO. XRD and fluorescence spectroscopy have shown that the use of DMSO promotes the formation of perovskite films that are less sensitive to moisture and irradiation. It is shown that the mobility of charge carriers in perovskite films obtained from DMSO (μ = 67 ± 5 cm2/V·s) is an order of magnitude higher than for the films obtained from DMF (μ = 9.1 ± 0.7 cm2/V·s). The density of charge carriers is n = (3.8 ± 0.3)·1019 cm-3 and n = (2.9 ± 0.2)·1019 cm-3 when using DMF and DMSO solvents, respectively. The formed organic–inorganic perovskite films with DMSO were found to have higher conductivity than films obtained from DMF. [ABSTRACT FROM AUTHOR]

The influence of DMF and DMSO solvents on the properties of organic–inorganic perovskite films obtained at the ratio of starting reagents PbI2:CH3NH3I = 1:2 was studied. It was found that a dense film is formed from solutions in DMSO. XRD and fluorescence spectroscopy have shown that the use of DMSO promotes the formation of perovskite films that are less sensitive to moisture and irradiation. It is shown that the mobility of charge carriers in perovskite films obtained from DMSO (μ = 67 ± 5 cm2/V·s) is an order of magnitude higher than for the films obtained from DMF (μ = 9.1 ± 0.7 cm2/V·s). The density of charge carriers is n = (3.8 ± 0.3)·1019 cm-3 and n = (2.9 ± 0.2)·1019 cm-3 when using DMF and DMSO solvents, respectively. The formed organic–inorganic perovskite films with DMSO were found to have higher conductivity than films obtained from DMF. [ABSTRACT FROM AUTHOR]

The current work presents structural change and band gap tunability using hybrid organic-inorganic perovskite with the incorporation of long chain ammonium halide. Thin films of MAPbI3 with different ratio of n-butylammonium iodide (BAI) have been successfully deposited on the substrate using a single step coating technique. X-ray diffraction scans revealed the transition of the 3D structure of MAPbI3 to quasi-2D perovskite structure when BAI loading increase with a crystallite size range approximately 16 nm. This structural changeis reflected in the band gap as it increased from 1.59 eV for bulk crystal MAPbI3 to 2.13 eV for BAI and MAPbI3 ratio of 1:1. Correspondingly, photoluminescence measurement showed a blue shift in perovskite emission due to the transition of 3D to 2D layered structure perovskite. Raman spectra confirm that all fabricated films are of pristine quality and no corresponding degradation peaks of PbI2 is observed. These characteristics are important to address the single step deposition method of hybrid perovskite for perovskite solar cells application.

• Time-resolved Scanning Electron Microscopy dynamically maps surface photovoltages. • Reversible photo-induced polarization of MAPbI3 films. • Sub-damage threshold conditions for optical and electronic excitation in MAPbI3. • Boundary condition dependence in light-assisted secondary electron contrast imaging. We introduce laser-assisted Time-Resolved SEM (TR-SEM), joining Scanning Electron Microscopy and laser light excitation, to probe the long-term temporal evolution of optically excited charge distributions at the surface of Metal Ammonium Lead Triiodide (MAPbI 3) hybrid perovskite thin films. Laser-assisted TR-SEM relies on the optically induced local modification of Secondary Electron (SE) detection yield to provide mapping of photoexcited potentials and charge dynamics at surfaces, and qualifies as a complementary approach to near-field probe microscopies and nonlinear photoemission spectroscopies for photovoltage measurements. Real-time imaging of evolving field patterns are provided on timescales compatible with SEM scanning rates, so that temporal resolution in the millisecond range can be ultimately envisaged. MAPbI 3 is an outstanding light-sensitive material candidate for applications in solar light harvesting and photovoltaics, also appealing as an active system for light generation. In this work, the real time temporal evolution of optically induced SE contrast patterns in MAPbI 3 is experimentally recorded, both under illumination by a 405 nm blue laser and after light removal, showing the occurrence of modifications related to photoinduced positive charge fields at surface. The long term evolution of these surface fields are tentatively attributed to ion migration within the film, under the action of the illumination gradient and the hole collecting substrate. This optical excitation is fully reversible in MAPbI 3 over timescales of hours and a complete recovery of the system occurs within days. Permanent irradiation damage of the material is avoided by operating the SEM at 5 keV of energy and 1–10 pA of primary current. Optical excitation is provided by intense above-bandgap illumination (up to 50 W/cm2). TR-SEM patterns show a strong dependence on the geometry of SE collection. Measurements are taken at different axial orientations of the sample with respect to the entrance of the in-column detection system of the SEM and compared with numerical modeling of the SE detection process. This enables to single out the information regarding the local potential distribution. Results are interpreted by combining data about the spectral distribution of emitted SEs with the configuration of the electric and magnetic fields in the specimen chamber. The present modeling sets a robust basis for the understanding of photoinduced SE electron contrast. [ABSTRACT FROM AUTHOR]

Highlights • Resistive switching behaviours in ITO/CH 3 NH 3 PbI 3 /metal memory devices. • Variation of metal contacts using Al, Ag, and Au. • Resistive Random Access Memory behaviour using Al as metal contact. • Write-Once-Read-Many characteristics in Ag and Au metal contacts. Abstract The utilization of defects in organic-inorganic hybrid perovskite materials such as CH 3 NH 3 PbI 3 is beneficial for memory applications. In this work, a simple CH 3 NH 3 PbI 3 memory device with various commonly used electrodes such as aluminium (Al), silver (Ag), and gold (Au) yielded different switching behaviours. Using Al in ITO/CH 3 NH 3 PbI 3 /Al device reveals Resistive Random Access Memory (ReRAM) behaviour with a SET voltage of 4.5 V and can be RESET by applying a negative sweep voltage above 1.3 V due to the formation of iodide vacancy filament. Interestingly, by using Ag and Au cathodes to replace Al, yielded Write-Once-Read-Many (WORM) resistive switching characteristics. The conversion process from OFF to ON occur at around 4.7 V and 4.0 V for Ag and Au, respectively. The "shorting effect" remains even though a reverse voltage was applied indicating data retention. These fabricated devices could contribute to further understanding of selecting the right electrodes and open up new possibility of studies in the direction of resistive switching memory applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The stability is improved due to the doping of lighter atoms. • Distinct blueshift implied reduction of optical properties in mixed structures. • Different doping positions in same phases are considered. • CH 3 NH 3 Pb(I 0.75 Br 0.25) 3 was chosed as the most potential optical material. Abstract Recently, extensive studies have widely fabricated and demonstrated that organic-inorganic hybrid perovskite-type solar cells, CH 3 NH 3 PbI 3 , have the superior optoelectronic properties. We explore the structural, electronic, optical properties and stability of tetragonal phase mixed halide perovskites CH 3 NH 3 Pb(I 1-y X y) 3 (X = Cl, Br; y = 0, 0.25, 0.5, 0.75), using first-principles calculations. The calculation of electronic structure reveals that the valance band maximum is governed by the halide p -orbitals and Pb 6 s -orbitals while the conduction band minimum formed by the mixed contribution from the p orbitals of Pb atom and s orbitals of I atom. For the stability and optical properties of CH 3 NH 3 Pb(I 1-y X y) 3 , the absorption coefficients show a blueshift of the absorption onsets but their stabilities show gradually increase with the increasing of X contents. Three different doping occupation phases of MAPb(I 0.5 X 0.5) 3 demonstrate that the impact of doping positions in linear optical property cannot be neglected but there is no change in stability. On the basis of all calculated results, we conclude that the best accouplement between absorption coefficiency and stability can be achieved at y = 0.25 in CH 3 NH 3 Pb(I 1−y Br y) 3 perovskites. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are used in thin-film solar cells, which owe their high efficiency to the long lifetimes of photocarriers. Various calculations find that a dynamical Rashba effect could significantly contribute to these long lifetimes. This effect is predicted to cause a spin splitting of the electronic bands of inversionsymmetric crystalline materials at finite temperatures, resulting in a slightly indirect band gap. Direct experimental evidence of the existence or the strength of the spin splitting is lacking. Here, we resonantly excite photocurrents in single crystalline (CH3NH3)PbI3 with circularly polarized light to clarify the existence of spin splittings in the band structure. We observe a circular photogalvanic effect, i.e., the photocurrent depends on the light helicity, in both orthorhombic and tetragonal (CH3NH3)PbI3. At room temperature, the effect peaks for excitation photon energies ΔE = 110 meV below the direct optical band gap. Temperaturedependent measurements reveal a sign change of the effect at the orthorhombic-tetragonal phase transition, indicating different microscopic origins in the two phases. Within the tetragonal phase, both ΔE and the amplitude of the circular photogalvanic effect increase with temperature. Our findings support a dynamical Rashba effect in this phase, i.e., a spin splitting caused by thermally induced structural fluctuations which break inversion symmetry. [ABSTRACT FROM AUTHOR]

The power conversion efficiency of organic–inorganic halide perovskite solar cells has exceeded 20% because of the outstanding properties of perovskite materials. However, the practical application of perovskite solar cells is hindered by their poor stability, which is related to the ion transport properties of perovskite materials. In this study, we explore an effective approach for reducing the migration of ions and improving the stability of solar cells by using mixed organic–inorganic perovskites. The structural and electronic properties of the mixed halide perovskites, namely, FMRCPbI and FMRCPbI, with various cation vacancies ( V MA ' , V FA ' , V Cs ' , and V Rb ' ) and the organic cation migration effects of MAPbI 3 , FAPbI 3 , and mixed FMRCPbI 3 perovskites were investigated using first-principles method. FA cations exhibit high activation energy in the mixed FMRCPbI perovskite, suggesting that the diffusion of FA cations in FMRCPbI mixed perovskite is suppressed. In addition, radiation recombination is slightly small in FMRCPbI with a high concentration of cation vacancies due to the absence of energy levels of vacancy defects in the band gap. With its relatively low recombination loss and direct band gap with high absorption coefficient and high thermal stability, FMRCPbI mixed perovskite may be a new generation of highly efficient and emissive perovskites for photovoltaics and photoemission applications. [ABSTRACT FROM AUTHOR]

Abstract: Perovskite/silicon tandem solar cells are increasingly recognized as promi­sing candidates for next‐generation photovoltaics with performance beyond the single‐junction limit at potentially low production costs. Current designs for monolithic tandems rely on transparent conductive oxides as an intermediate recombination layer, which lead to optical losses and reduced shunt resistance. An improved recombination junction based on nanocrystalline silicon layers to mitigate these losses is demonstrated. When employed in monolithic perovskite/silicon heterojunction tandem cells with a planar front side, this junction is found to increase the bottom cell photocurrent by more than 1 mA cm−2. In combination with a cesium‐based perovskite top cell, this leads to tandem cell power‐conversion efficiencies of up to 22.7% obtained from J–V measurements and steady‐state efficiencies of up to 22.0% during maximum power point tracking. Thanks to its low lateral conductivity, the nanocrystalline silicon recombination junction enables upscaling of monolithic perovskite/silicon heterojunction tandem cells, resulting in a 12.96 cm2 monolithic tandem cell with a steady‐state efficiency of 18%. [ABSTRACT FROM AUTHOR]

The influence of the synthesis conditions (rotation speed used for spin-coating deposition of the film, film drying temperature, and the ratio of the PbI2 and CH3NH3I reactants in solutions) on the microstructure, phase composition, and spectral-luminescent properties of films of organic-inorganic perovskite CH3NH3PbI3-xClx (x = 0, 0.02) was elucidated. [ABSTRACT FROM AUTHOR]

The influence of the synthesis conditions (rotation speed used for spin-coating deposition of the film, film drying temperature, and the ratio of the PbI2 and CH3NH3I reactants in solutions) on the microstructure, phase composition, and spectral-luminescent properties of films of organic-inorganic perovskite CH3NH3PbI3-xClx (x = 0, 0.02) was elucidated. [ABSTRACT FROM AUTHOR]

Organic-inorganic perovskite solar cells have experienced a remarkable development. In a short period of time power conversion efficiencies have jumped to values of more than 22%. However, the stability of these devices is an important subject. The stability of CH3NH3PbI3 perovskite films is investigated using visible and ultraviolet light in oxygen atmosphere and in vacuum. Illumination in O2 atmosphere results in a swift degradation. Oxygen acts as a catalyst decomposing methylammonium ions (CH3NH3+) into CH3NH2 and hydrogen. In vacuum, another degradation mechanism is observed. Prolonged illumination of the samples with photons from blue and UV light-emitting diodes also results in dissociation of the methylammonium ion into CH3NH2 and hydrogen. In both cases the resulting molecules are highly mobile at room temperature and diffuse out of the samples. The light-induced dissociation of CH3NH3+ is accompanied by the generation of localized defects in the band gap of the perovskite. Furthermore, the experimental data clearly show that the molecular orbitals of CH3NH3+ are not in resonance with the energy bands of the perovskite lattice. [ABSTRACT FROM AUTHOR]

Methylammonium lead-halide perovskites are very promising for applications as solar light-harvesting materials. This paper presents a study on the methylammonium iodide and iodide-chloride perovskite films prepared by spin coating from a liquid precursor. The powder diffraction spectroscopy has detected 10 lattice plane reflections common to a perovskite of a tetragonal crystal structure. The calculated cell parameters are a = 8.85 Å and c = 12.60 Å. The preparation conditions and their impact on the crystallization process and film morphology are discussed. A red shift of photoluminescence bands at low temperatures was evidenced. A photoelectrical study of perovskite films has revealed their high sensibility to illumination, especially in the visible spectrum, which gives a hint on their applications in photovoltaics. [ABSTRACT FROM AUTHOR]

In this study, the features of resistive random access memory (RRAM) employing a straightforward Cr/MAPbI 3 /FTO three-layer structure have been examined and clarified. The device displays various resistance switching (RS) behavior at various sweep voltages between 0.5 and 5 V. The RS effect has a conversion in the direction of the SET and RESET processes during sweeping for a number of cycles at a specific voltage. The directional change of the RS processes corresponds to the dominant transition between the generation/recombination of iodide ion and vacancy in the MAPbI 3 perovskite layer and the electrochemical metallization of the Cr electrode under the influence of an electric field, which results in the conductive filament (CF) formation/rupture. At each stage, these processes are controlled by specific charge conduction mechanisms, including Ohmic conduction, space-charge-limited conduction (SCLC), and variable-range hopping (VRH). By identifying the biased voltage and the quantity of voltage sweep cycles, one can take a new approach to control or modulate the pathways for effective charge transport. This new approach is made possible by an understanding of the RS characteristics and the corresponding mechanisms causing the variation of RS behavior in the structure., (© 2023 Wiley-VCH GmbH.)

Despite great progress in perovskite photovoltaics, it should be noted that the intrinsic disorder dipolar cations in organic-inorganic hybrid perovskites exert negative effects on the energy band structure as well as the carrier separation and transfer dynamics. However, oriented polarization achieved by applying an external electric field may cause irreversible damage to perovskites. Herein, a unique and efficient strategy is developed to modulate the intrinsic dipole arrangement in perovskite films for high-performance and stable perovskite solar cells (PSCs). The spontaneous reorientation of dipolar cation methylamine is triggered by a polar molecule, constructing a vertical polarization during crystallization regulation. The oriented dipole determines a gradient energy-level arrangement in PSCs and more favorable energetics at interfaces, effectively enhancing the built-in electric field and suppressing the nonradiative recombination. Besides, the dipole reorientation induces a local dielectric environment to remarkably reduce exciton binding energy, leading to an ultralong carrier diffusion length of up to 1708 nm. Accordingly, the n-i-p PSCs achieve a significant increase in power conversion efficiency, reaching 24.63% with negligible hysteresis and exhibiting outstanding stabilities. This strategy also provides a facile route to eliminate the mismatched energetics and enhance carrier dynamics for other novel photovoltaic devices., (© 2023 Wiley-VCH GmbH.)

We present the preparation and characterization of solution processed lead free films of zero-dimensional methylammonium iodo bismuthate (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite. Structural characterization reveals the formation of hexagonal micro-crystals with preferred growth orientation along the c -axis. The material exhibits a wide band gap of 2.9 eV and upon optical excitation the photoluminescence emission is observed at 1.65 eV (751 nm). Photoelectron spectroscopy confirms the stoichiometry of the (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite and yields an ionization energy of 6.24 eV, while Raman spectra confirm the vibrational modes of the bioctahedral inorganic anion framework (Bi 2 I 9 ) 3− in the low wavenumber regime (<200 cm −1 ) regime. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) are employed to evaluate the experimental results. We apply this novel bismuth-based hybrid perovskite in proof of principle simple heterojunction solar cell devices, which yield power conversion efficiencies of ~0.1%. Further enhancement is expected once the film morphology and device stack are optimized. [ABSTRACT FROM AUTHOR]

We demonstrate that double spin coating, where a perovskite film is covered with another perovskite film, can increase substrate coverage from 81% to 97% along with an increase of film thickness from 151 ± 17 to 246 ± 18 nm. The increased substrate coverage by double coating improves the solar power conversion efficiency from 7.1 ± 0.6 to 10.3 ± 1.0%, an approximate 1.5-fold increase. Additionally, a double-coated film of higher substrate coverage exhibits amplified spontaneous emission (ASE) while a single-coated film of lower substrate coverage does not exhibit ASE. Double coating is an attractive method for increasing substrate coverage and improving solar power conversion and ASE. [ABSTRACT FROM AUTHOR]

To improve the electroluminescence efficiency of organic-inorganic hybrid perovskite (OIP) films, we need to consider several different types of post-treatments after film formation such as thermal annealing and solvent annealing. Here, we only applied thermal treatment on the film excluding all the other treatments. Then, we analyzed the effects of annealing time t ann on crystallinity of methylammonium lead bromide (CH 3 NH 3 PbBr 3 ) films and on luminous efficiency of CH 3 NH 3 PbBr 3 -based perovskite light-emitting diodes (PrLEDs). When thermal annealing of CH 3 NH 3 PbBr 3 films was conducted at 90 °C, t ann ≤ 10 min increased its crystallinity by eliminating residual solvent and completing the conversion of precursor to crystal, but t ann > 10 min reduced crystallinity and caused slight sublimation of CH 3 NH 3 Br. This was consistent with trend of the luminous efficiency of our PrLEDs that showed the optimum performance at t ann = 10 min. These results demonstrate that optimizing t ann of CH 3 NH 3 PbBr 3 films is a simple way to improve the luminous efficiency of PrLEDs by controlling their crystallinity. [ABSTRACT FROM AUTHOR]

Organolead halide perovskites (e.g., CH3NH3PbI3) have caught tremendous attention for their excellent optoelectronic properties and applications, especially as the active material for solar cells. Perovskite crystal quality and dimension is crucial for the fabrication of high-performance optoelectronic and photovoltaic devices. Herein the controlled synthesis of organolead halide perovskite CH3NH3PbI3 nanoplatelets on SiO2/Si substrates is investigated via a convenient two-step vapor transport deposition technique. The thickness and size of the perovskite can be well-controlled from few-layers to hundred nanometers by altering the synthesis time and temperature. Raman characterizations reveal that the evolutions of Raman peaks are sensitive to the thickness. Furthermore, from the time-resolved photoluminescence measurements, the best optoelectronic performance of the perovskite platelet is attributed with thickness of ≈30 nm to its dominant longest lifetime (≈4.5 ns) of perovskite excitons, which means lower surface traps or defects. This work supplies an alternative to the synthesis of high-quality organic perovskite and their possible optoelectronic applications with the most suitable materials. [ABSTRACT FROM AUTHOR]

Recently, intensive studies on the role of water molecule in the formation of organic-inorganic perovskite film have been reported. However, not only the contradictive phenomena but also the complex processing technique has hindered the widespread use of water molecule in perovskite preparation. Here the hydration water is introduced into the precursors instead of water. By precisely controlling the content of hydration water, a smoother and more uniform perovskite film is obtained through a simple one-step spin coating method. The improvement of perovskite film quality leads to highly efficient planar perovskite solar cells. Summing up the device studies and the investigation of morphology, crystallization, and optical properties, the impact of water molecule in the formation of perovskite crystal and consequences of device performance is understood. Due to its universal adaptability and simplified process, precise control of hydration water is therefore of great utility to high quality perovskite films fabrication and large-scale production of this upcoming photovoltaic technology. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic perovskites have attracted considerable attention after promising developments in energy harvesting and other optoelectronic applications. However, further optimization will require a deeper understanding of the intrinsic photophysics of materials with relevant structural characteristics. Here, the dynamics of photoexcited charge carriers in large-area grain organic-inorganic perovskite thin films is investigated via confocal time-resolved photoluminescence spectroscopy. It is found that the bimolecular recombination of free charges is the dominant decay mechanism at excitation densities relevant for photovoltaic applications. Bimolecular coefficients are found to be on the order of 10−9 cm3 s−1, comparable to typical direct-gap semiconductors, yet significantly smaller than theoretically expected. It is also demonstrated that there is no degradation in carrier transport in these thin films due to electronic impurities. Suppressed electron-hole recombination and transport that is not limited by deep level defects provide a microscopic model for the superior performance of large-area grain hybrid perovskites for photovoltaic applications. [ABSTRACT FROM AUTHOR]

In this paper, we present a study of the structural and optical properties of organic–inorganic halide-based perovskite semiconductors with band gaps varying from NIR to visible at room temperature. Thin films of nanocrystalline CH 3 NH 3 PbI 3 with different concentrations of methylammonium iodide (MAI) have been successfully deposited onto glass substrates using single step spin-coating technique. The prepared films have been characterized by X-ray diffraction, optical absorption spectroscopy and photoluminescence measurements. X-ray diffraction scans revealed that even for stoichiometric atomic concentrations of MA:Pb:I of 1:1:3, the PbI 2 phase was also present. The PbI 2 phase showed a highly textured along the (001) direction in all the prepared films, with a crystallite size in the range of approximately 30–40 nm. The optical absorbance edge of CH 3 NH 3 PbI 3 thin films is described in terms of direct transition model proposed by Tauc in the strong absorption region. The band gap of the pure PbI 2 film was calculated to be 2.40 eV, whereas the band gap of the pervoskite film with stoichiometric ionic ratio of 1:1 PbI 2 and CH 3 NH 3 I was calculated to be 1.46 eV, while absorption coefficient is ~10 5 cm −1 . Photoluminescence measurements showed a red shift in the perovskite emission with increasing the MAI concentration, confirming the correct placement of the MA ions in the perovskite crystalline structure showing the PbI 2 octahedra. Our results confirm the existence of PbI 2 phase in the highly efficient perovskite solar cells, as demonstrated in the recent publication. [ABSTRACT FROM AUTHOR]

In this paper luminescent solar concentrators (LSCs) based on CH 3 NH 3 PbBr 3 perovskite quantum dots (QDs) and QDs containing gold nanoparticles (NPs) with flat and half-cylindrical geometries are introduced. Excitonic and PL emission peaks at 512 nm and 539 nm with majority average size of 16 nm are the characteristics of the synthesized lead bromide perovskite QDs. Incorporation of synthesized spherical gold NPs with an average diameter of 13 nm and absorption peak at 527 nm in perovskite based LSCs are also investigated. The measured reabsorption loss is decreased for LSCs in the presence of gold NPs. The PCE of edge-mounted solar panel in sheet LSCs based on gold NPs doped QDs, is enhanced with respect to CH 3 NH 3 PbBr 3 QD based LSCs, due to plasmonic effect of gold NPs. Varying the LSC geometry to half-cylinder improves the device performance by effectively concentrating of incident light into the solar panel. The effect of backscatterers is also investigated for bottom-mounted solar panel in new half-cylindrical geometry. The best device efficiency is obtained for the white backgrounded LSC, since it could act as a scatter to send back the lost light into the LSC, efficiently. [Display omitted] • Lead bromide based Luminescent solar concentrators (LSCs) are fabricated in flat sheet and novel half-cylindrical geometries. • Doping Au NPs to perovskite QDs decreases the reabsorption and boosts the overall output power of LSC devices. • The PCE of half-cylindrical LSC devices are higher than sheet LSCs, due to the lens-like behavior of half-cylinders. • The white back scatterer improves the efficiency of half-cylindrical LSC devices more than mirror and black scatterers. [ABSTRACT FROM AUTHOR]

Perovskite-structured organic–inorganic materials such as CH 3 NH 3 PbI 3 are attracting much interest in the scientific community because of their abilities to function as revolutionary light harvesters and charge transfer materials for solar cells. To achieve high power conversion efficiency (PCE), it is critical to optimize the perovskite film layer. This paper reports the temperature and concentration controls on the two-step solution process. A diffusion-controlled growth mechanism is proposed for this process in tuning the morphology and purity of the perovskite film, which are proven to be important factors contributing to the photovoltaic performance. The highest PCE of 11.92% is achieved with an optimized perovskite crystal size of ∼150 nm and an appropriate amount of residual PbI 2 . This study sheds light on the design and fabrication of highly efficient, low-cost, solution-processed perovskite solar cells. [ABSTRACT FROM AUTHOR]

The Luminescent solar concentrators (LSCs) consist of a film containing optically active centers, converting part of the absorbing radiation into a specific emitting wavelength, when exposed to sunlight. The emitting centers are also crucial factors regarding their efficiency, so the selection must be done carefully. Here, we introduce organometal halide perovskite as a new class of phosphors, to use in luminescent solar concentrators. The coating of a Si PV cell with an organometal halide perovskite is tested. The obtained results reveal that, to find a suitable condition for effective LSC, it is necessary to determine appropriate molar ratio of organic and inorganic portion in synthesis perovskite, as well as concentration of halide perovskite in LSC. It is found that CH 3 NH 3 PbBr 3 perovskite with the CH 3 NH 2 /PbBr 2 : 6/1 M ratio and 7.0 wt% perovskite concentration in Polyvinyl Alcohol (PVA) leads to the highest efficiency (increased about 45%, compared to uncoated cell). [ABSTRACT FROM AUTHOR]

Perovskite-sensitized nanoporous TiO 2 films with different thicknesses are prepared by an in situ method, which are employed as photoanodes in perovskite solar cells (PSCs). The photoelectrochemical properties of different photoanodes are quantified by the ultraviolet to visible reflectance spectra, incident monochromatic photon-to-current conversion efficiency, and electrochemical impedance spectroscopy measurements. Results demonstrate that the thin photoanode has high electron lifetime for recombination, which can enhance the separation and transmission of the electron and hole. However, the sunlight utilization will decrease with reducing the photoanode thickness due to the small quantity of CH 3 NH 3 PbI 3 filled into the photoanode to absorb sunlight. After optimization, PSC with 0.80 μm of the photoanode thickness shows a superior cell efficiency of 12.22% without a hole transporting material. [ABSTRACT FROM AUTHOR]

Highlights: [•] Porous anodic alumina (PAA) were prepared in a two-step anodizing process. [•] Organic–inorganic perovskite embedded on PAA. [•] Confinement effect of the incorporation of perovskite compounds quantum wells into different porous anodic aluminum. [•] New approach to stabilize the organic–inorganic perovskite crystal for optoelectronic devises applications. [Copyright &y& Elsevier]