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Undoped titanium dioxide (TiO2) films were successfully doped with cationic cesium (Cs+) at different molar concentrations on a glass substrate via a two-step spin coating method. Undoped and cesium-doped methylammonium lead iodide (CH3NH3PbI3) materials were prepared and deposited on the titanium dioxide films via a one-step spin coating process. The structure, morphology, elemental, and optical characteristics of the synthesized materials were respectively studied using X-ray diffractometer, scanning electron microscope, energy dispersive X-ray spectrophotometer (EDX), and ultraviolet–visible spectroscope. The structural result revealed crystalline peaks which became more prominent at increasing dopant concentration. Clustered nanospheres were observed from the morphological results with the presence of agglomerates. EDX results showed the presence of basic elemental constituents for the undoped and doped samples which confirms the deposition of the as-deposited elements. The optical results of the films showed good features with energy band gap values ranging from 2.03 eV to 1.98 eV for the undoped and doped samples. The prepared films are potentially applied in optical and solar cell devices. [ABSTRACT FROM AUTHOR]

Because of its interesting optoelectronic properties, Methylammonium Lead Iodide CH3NH3PbI3 perovskite semiconductor is used as an active layer in the development of several emerged solar cells. In this work, the solar cell with the architecture FTO/TiO2/ CH3NH3PbI3/Spiro-MeOTAD/Au is simulated using the sophisticated OghmaNano software. We have studied the influence of some parameters like thickness for different layers, charge carrier mobility of holes and electrons, charge recombination rate, band gap energy and doping in the active layer. The effect of device temperature is also studied. The photovoltaic characteristic curves such as Current density-Voltage (J-V), is represented in this work. The final optimized parameters Jsc, Voc, FF and PCE are 34.14 mA/cm², 0.95 Volt, 82.28 % and 26.13 % respectively. [ABSTRACT FROM AUTHOR]

Intrinsic defects have a significant impact on carrier transport properties of Methyl Ammonium Lead Iodide (MAPI) Perovskite CH3NH3PbI3. In this paper, we investigated how lead vacancies affect the photovoltaic properties of MAPI using density functional theory (DFT) studies. Lead vacancies in perovskite materials can significantly impact carrier dynamics and device efficiency. Our findings indicate that the lower energy configuration of the Pb vacancy does not create deep trap states that would otherwise reduce carrier lifetime. This suggests that Pb vacancies in MAPI might not be as detrimental to carrier dynamics as previously thought. Pb vacancies could potentially be compensated by other defects or dopants in the material, which might mitigate their negative effects on carrier dynamics. The introduction of a Pb vacancy leads to additional electronic states near the conduction band minimum (CBM) within the fundamental band gap. This indicates that the vacancy introduces localized electronic states that influence carrier behavior. The Highest Occupied Molecular Orbital (HOMO) becomes more localized around the vacant area, while the Least Unoccupied Molecular Orbitals (LUMOs) are only partially localized. This localization around the vacancy does not create strong trapping states that could hinder carrier movement. The presence of vacancies causes atomic movements that result in a more distorted optimized structure. This structural distortion can influence the overall material properties and potentially impact device performance. The HOMO and LUMO levels are primarily derived from the p orbitals of the atoms involved. This highlights the importance of p orbital interactions in determining the electronic properties of the material

The perovskite solar cells (PSCs) reveal the impressive performance due to the extraordinary characteristic features of perovskite material and its fabrication methods. The complex deposition process and hygroscopic nature of hole transport materials are biggest obstacles for attaining high power conversion efficiency (PCE) with long term stability in PSC. In this study, NiO/MWCNT nanocomposites have been synthesized by hydrothermal method and are incorporated in CH 3 NH 3 PbI 3 to increase the performance of PSCs with stability. The incorporation has been carried out to improve the properties of CH 3 NH 3 PbI 3 such as formation of large grain size/grain boundaries, reduce the defects that enhance the charge generation/collection and reduction in recombination. The fabricated PSCs with NiO/MWCNT revealed a PCE of 14.93 % with moderate hysteresis, which is significantly higher PCE than that of pristine PSC. The enhanced recombination resistance was observed by electrochemical impedance spectroscopy, which evinces the remarkable PCE of NiO/MWCNT incorporated PSC. The strong PL quenching and red shift of PL spectrum confirms the low recombination and larger grains in the NiO/MWCNT-CH 3 NH 3 PbI 3 layer. Moreover, the NiO/MWCNT incorporated PSC retains 94 % of its initial PCE after 600 h of aging under atmospheric condition whereas the PCE of pristine PSC shows 87 % of its initial PCE value. The carbon back electrode also supports to lift up PCE and stability of PSCs. [ABSTRACT FROM AUTHOR]

Past few years has witnessed a rapid surge in the design and fabrication of lead halide perovskite solar cells (LH‐PSCs). Methyl ammonium lead iodide (CH3NH3PbI3) is one of the widely used visible light absorbing material towards the fabrication of LH‐PSCs. The CH3NH3PbI3 has a band gap of around 1.55 eV which makes it a suitable visible light sensitizer for the development of high performance next generation LH‐PSCs. In this work, CH3NH3PbI3 has been explored as visible light absorbing layer with mesoscopic device architecture of (FTO/TiO2/CH3NH3PbI3/spiro‐OMeTAD+MoS2/Au) LH‐PSCs. MoS2 has been utilized as hole transport material additive which not only acted as additive but also enhanced the performance of the LH‐PSCs with long term stability. The FTO/TiO2/CH3NH3PbI3/spiro‐OMeTAD+MoS2/Au showed the interesting efficiency of 14.2 % which is higher than that of the FTO/TiO2/CH3NH3PbI3/spiro‐OMeTAD/Au device (11.9 %). This work offers the fabrication of stable and improved LH‐PSCs with device architecture of FTO/TiO2/CH3NH3PbI3/spiro‐OMeTAD+MoS2/Au. [ABSTRACT FROM AUTHOR]

An experimental investigation has been undertaken to explore a variety of properties of organic perovskite solar cells (OPSCs) that are distinct in their photovoltaic response. In this study, OPSCs were constructed using zinc oxide, ZnO and [6,6]-phenylC 6 1 -acid methyl ester, PCBM, as electron transfer materials (ETM), poly(3-hexylthiophene), P3HT, as hole transport material (HTM), and CH3NH3PbIX2 as a photosensitizer, where X is either Cl or I. The structural and optical characteristics of the ETM and HTM layers and the perovskite materials of OPSCs were investigated. The I – V and P – V curves of each solar cell prepared in OPSCs were measured using an integrated cell tester. This comprises a photovoltaic I – V measurement system and a solar simulation system. As a result of these results, the OPSC's performance is evaluated. The calculations in this work suggest that the highest power conversion efficiency (PCE = 6.31%) was achieved in photovoltaic devices using CH3NH3PbI3 as the effective absorber layer and ZnO with PCBM as the ETM layer. At a light intensity of 100 mW/cm2, each OPSC cell was performed. Under the same conditions, the I – V curves were evaluated for each OPSC device. By improving the selection of organic and inorganic active materials in the ETM layer, OPSC performance may be improved. [ABSTRACT FROM AUTHOR]

Currently, organic–inorganic metal halide perovskite material based Photovoltaic cell have achieved an impressive level of success due to their unique properties in the photovoltaic industry. In this paper, primary goal is to examine and compare the characteristics of performance of Pb, Sn and Ge perovskite solar cell structure with additional hole transport and back surface field layer of group IV alloy to achieve the improved efficiency. The simulated device structure consists of electron transport/absorber/hole-transport/back surface field layers where SnO2 material used for electron transport layer (ETL), SiGe and Spiro-OMeTAD materials used for transporting hole layers (HTLs), back-surface field (BSF) layer is of SiGeSn and perovskite absorber layer material are CH3NH3PbI3, CH3NH3SnI3, CH3NH3GeI3, respectively. A comparative analysis is made between three different solar cell structures which is based on Pb, Sn and Ge perovskite material. Higher conversion efficiency is obtained with Pb perovskite solar cell in comparison to Sn and Ge based solar cells. CH3NH3PbI3 exhibits better conversion efficiency as compared to the CH3NH3SnI3 and CH3NH3GeI3 while using the same layer thickness. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) show a great promise for high-efficiency and cost-effective photovoltaic devices. This study focuses on the use of beta-gallium oxide (β-Ga2O3) as a versatile component in PSCs. β-Ga2O3 serves as the electron transport layer (ETL), a window material that reduces reflection of visible light, a UV absorption layer for perovskite stability, and a hole blocking layer (HBL) due to its high valence band-offset. Additionally, a bilayer of cuprous oxide/silicon (Cu2O/p-Si) is employed as the hole transport and electron blocking layer (HTL and EBL), while methylammonium lead iodide (CH3NH3PbI3) serves as the perovskite absorber. Numerical simulations using SILVACO-TCAD demonstrate that replacing ZnO with β-Ga2O3 as the ETL leads to a significant enhancement in PSC performance. The optimized device exhibits a power conversion efficiency (PCE) of 23.02%, an open circuit voltage (Voc) of 0.95 V, a short circuit current density (Jsc) of 31.12 mA/cm2, and a fill factor (FF) of 77.53%. The study highlights the benefits of using β-Ga2O3 and Cu2O/p-Si in PSCs, emphasizing their crucial role in improving device performance. Our findings will help perovskite solar cells designers to eliminate one of the causes of stability which is UV radiations by absorption utilizing a β-Ga2O3 layer at the front and which acts as an ETL and a window as well, hence contributing to material and cost reduction. The Cu2O/p-Si used as an HTL the PSC achieve a PCE close to the Shockley–Queisser limit which is 26.6%. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are considered important materials for the fabrication of high‐performance optoelectronic devices. However, the poor quality of thin films with abundant grain boundaries and defect states greatly lower the performance and stability of as‐fabricated devices. In the present work, the growth of improved perovskite CH3NH3PbI3 thin films through Co‐based zeolite imidazole framework (ZIF‐67) additive assisted Co ion doping is reported. Investigation of the morphological, structural, optical, and electrical properties shows that the Co ion doped CH3NH3PbI3 (CH3NH3Pb0.98Co0.02I3) thin films exhibit low grain boundaries, low defect states, and improved structural stabilities. The positive roles of suppression of defect states are further demonstrated by improved performance and stability of photodetectors based on CH3NH3Pb0.98Co0.02I3 thin films. Finally, density functional theory calculations are performed to reveal the mechanisms of passivation of undercoordinate Pb2+ vacancy defect states by Co ion doping. The results provided in this work will pave the way toward the fabrication of high performance and stable perovskite photodetectors in the future. [ABSTRACT FROM AUTHOR]

The defect states and photoelectric conversion efficiency (PCE) were studied in the CH3NH3PbI3 (MAPbI3) solar cell with SnO2 by varying the application time of ethyl acetate antisolvent from 4 to 0.3 s. As the application time was decreased, the surface morphology of MAPbI3 thin films became smoother and its grain size was increased to 174 nm. In the device structure of Au/MAPbI3/SnO2/ITO/glass, when the application time was decreased to 0.6 s, the reverse saturation current density (Jo) was decreased by 5.34 × 10–6 A cm−2, and the highest PCE of 15.51% was achieved. However, as the application time was further decreased to 0.3 s, Jo increased up to 1.49 × 10–4 A cm−2 and the PCE was decreased. From deep level transient spectroscopy measurements, two defect states E2 and H1 were observed. Although the activation energy (Ea), capture cross-section (σn) and defect density (Nt) of the E2 state showed different values from each device, real values of Ea, σn, and Nt for E2 could be determined to 0.73 ± 0.04 eV, 1.15 × 10–16 cm2 and 8.16 × 1015 cm−3, respectively, by considering different Jo values of the devices. Ea, σp, and Nt of the H1 state only appeared in the shortest application times as equal to 0.46 ± 0.03 eV, 1.09 × 10–16 cm2 and 9.66 × 1015 cm−3, respectively. [ABSTRACT FROM AUTHOR]

The experimental results of a perovskite solar cell with FTO/TiO2/CH3NH3PbI3/PEDOT:PSS/Pt cell architecture fabricated in our research laboratory under ambient conditions are compared with the simulated results obtained using SCAPS-1D. Optimization of the thickness of the perovskite, ETL and HTL, temperature, and the work function of the metal has been carried out to formulate a high-performance perovskite solar cell. The impacts of varying absorber thickness, ETL, temperature, and metal work function exhibit very minimal or no change. However, the device exhibits a high power conversion efficiency (PCE) in HTL thickness variation. The impact of variation in HTL thickness from 10 nm to 500 nm shows the best cell performance in terms of PCE between 10 nm and 50 nm. At 10-nm thickness, Jsc, Voc, FF, and PCE are 35.08 mA/cm2, 0.95 V, 35.08%, and 28.93%, respectively. The cell efficiency decreases with the increase in the thickness of HTL. However, at lower thicknesses, the extraction of the generated carrier is generally low. Therefore, analyzing all the results, we suggest that, to obtain a high power conversion (26.26% at 30 nm and 23.75% at 50 nm), the HTL thickness should effectively be between 30 nm and 50 nm. The structure of the studied solar cell device having such cell characteristics can be considered in the manufacturing workflow for its mass-scale production. [ABSTRACT FROM AUTHOR]

The optoelectronic response of organic perovskite solar cells (OPSCs) exhibits a variety of unique and distinguishing characteristics. In this study, OPSCs with photosensitizers, CH3NH3PbI2X, where X is I, Br, or Cl, are created using TiO2 as the electron transport material (ETM) and CuO as the hole transport material (HTM). The perovskite materials' structural and optical characteristics, as well as the OPSCs' ETM layers, are investigated. Next, the OPSC's performance is evaluated. The integrated cell tester, which includes the I-V photovoltaic measurements system and the solar simulation system, was used to measure the I-V curves of the OPSCs. The photovoltaic devices with MAPbI3 as an efficient absorption layer had the best power conversion efficiency (PCE = 4. 2 2 %). Measurements of the OPSC's performance were tested at 100 mW/cm2 of light intensity. [ABSTRACT FROM AUTHOR]

Today, it has become an important task to modify existing traditional silicon-based solar cell factory to produce high-efficiency silicon-based heterojunction solar cells, at a lower cost. Therefore, the aim of this paper is to analyze CH3NH3PbI3 and ZnO materials as an emitter layer for p-type silicon wafer-based heterojunction solar cells. CH3NH3PbI3 and ZnO can be synthesized using the cheap Sol-Gel method and can form n-type semiconductor. We propose to combine these two materials since CH3NH3PbI3 is a great light absorber and ZnO has an optimal complex refractive index which can be used as antireflection material. The photoelectric parameters of n-CH3NH3PbI3/p-Si, n-ZnO/p-Si, and n-Si/p-Si solar cells have been studied in the range of 20-200 nm of emitter layer thickness. It has been found that the short circuit current for CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells is almost the same when the emitter layer thickness is in the range of 20-100 nm. Additionally, when the emitter layer thickness is greater than 100 nm, the short circuit current of CH3NH3PbI3/p-Si exceeds that of n-ZnO/p-Si. The optimal emitter layer thickness for n-CH3NH3PbI3/p-Si and n-ZnO/p-Si was found equal to 80 nm. Using this value, the short-circuit current and the fill factor were estimated around 18.27 mA/cm2 and 0.77 for n-CH3NH3PbI3/p-Si and 18.06 mA/cm2 and 0.73 for n-ZnO/p-Si. Results show that the efficiency of n-CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells with an emitter layer thickness of 80 nm are 1.314 and 1.298 times greater than efficiency of traditional n-Si/p-Si for the same sizes. These findings will help perovskites materials to be more appealing in the PV industry and accelerate their development to become a viable alternative in the renewable energy sector. [ABSTRACT FROM AUTHOR]

The creation of ZnO/CH 3 NH 3 PbI 3 heterostructures with Aluminum (Al), Magnesium (Mg), and Indium (In) doped ZnO serving as an electron transport layer is the aim of this work. A favorable orientation for the CH 3 NH 3 PbI 3 absorber layer crystallizes in the tetragonal phase [220], while ZnO crystallizes in the hexagonal phase [100]. This information is yielded by x-ray diffraction analysis. Al, In, and Mg doping of the transport layer has a significant effect on the optical characteristics like absorption and extinction coefficients, optical gaps, and optical and electrical conductivity. The UV–visible characterization of the heterostructures reveals that n-type doping can raise ZnO gap energy from 3.15 to 3.42 eV. The band gap energy of CH 3 NH 3 PbI 3 is around 1.53–1.55 eV. Additionally, the absorption coefficient of each sample is high, it exceeds 105 cm−1. The ZnO thin films, both undoped and doped (with Al, In and Mg) exhibit an increase in refractive index from 1.97 to 2.13. The best dopant is found to be In. The refractive index of films composed of CH 3 NH 3 PbI 3 is 3.13. [ABSTRACT FROM AUTHOR]

Today, it has become an important task to modify existing traditional silicon-based solar cell factory to produce high-efficiency silicon-based heterojunction solar cells, at a lower cost. Therefore, the aim of this paper is to analyze CH3NH3PbI3 and ZnO materials as an emitter layer for p-type silicon wafer-based heterojunction solar cells. CH3NH3PbI3 and ZnO can be synthesized using the cheap Sol-Gel method and can form n-type semiconductor. We propose to combine these two materials since CH3NH3PbI3 is a great light absorber and ZnO has an optimal complex refractive index which can be used as antireflection material. The photoelectric parameters of n-CH3NH3PbI3/p-Si, n-ZnO/p-Si, and n-Si/p-Si solar cells have been studied in the range of 20–200 nm of emitter layer thickness. It has been found that the short circuit current for CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells is almost the same when the emitter layer thickness is in the range of 20–100 nm. Additionally, when the emitter layer thickness is greater than 100 nm, the short circuit current of CH3NH3PbI3/p-Si exceeds that of n-ZnO/p-Si. The optimal emitter layer thickness for n-CH3NH3PbI3/p-Si and n-ZnO/p-Si was found equal to 80 nm. Using this value, the short-circuit current and the fill factor were estimated around 18.27 mA/cm2 and 0.77 for n-CH3NH3PbI3/p-Si and 18.06 mA/cm² and 0.73 for n-ZnO/p-Si. Results show that the efficiency of n-CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells with an emitter layer thickness of 80 nm are 1.314 and 1.298 times greater than efficiency of traditional n-Si/p-Si for the same sizes. These findings will help perovskites materials to be more appealing in the PV industry and accelerate their development to become a viable alternative in the renewable energy sector. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structural stability and electronic properties of CH 3 NH 3 PbI 3 /ZnO were investigated using first-principles method. • The interfacial termination of CH 3 NH 3 PbI 3 influences the orientational order of C–N bonds and structural stability. • The spontaneous electric polarization plays an important role in high efficient separation and transport of carriers. • This study provide an in-depth understanding of the properties of CH 3 NH 3 PbI 3 /ZnO, and improve the performance of PSCs. The structural stability and electronic properties of CH 3 NH 3 PbI 3 /ZnO heterojunctions were investigated using first-principles method. Our results show that the interfacial termination of CH 3 NH 3 PbI 3 influences the orientational order of C–N bonds and structural stability of heterojunction. For the first time, it was confirmed that the ionic polarization of CH 3 NH 3 PbI 3 material in CH 3 NH 3 PbI 3 /ZnO induced by interfacial electrostatic interaction plays an important role in high efficient separation and transport of photo-generated carriers, which is a new physical mechanism. This study could provide an in-depth understanding of the properties of CH 3 NH 3 PbI 3 /ZnO, and improve the stability and performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

A detailed fabrication method is represented for perovskite solar cells, incorporating various materials and processes based on glove box-free sol-gel deposition routes. Key components include NiO x HTL, PC 61 BM ETL, BCP HBL, and CH 3 NH 3 PbI 3 perovskite absorber. Results reveal a significant influence of PC 61 BM concentration on device efficiency, with champion cells exhibiting optimized V OC , J SC , and FF values at a specific concentration. Statistical analysis of 38 devices confirms the reproducibility and consistency of this concentration, yielding a PCE of 18.2 %. This study investigates a gap in the literature by clarifying the impact of PC 61 BM solution concentration as a sol-gel deposited electron transport layer. By identifying the optimal concentration and its role in improving device efficiency and reproducibility, investigation contributes to advancing the field of fully sol-gel-based perovskite solar cell technology. [ABSTRACT FROM AUTHOR]

Organometallic halide-based perovskite solar cells have played a significant role in the development of photovoltaic technology. The synthesis of the perovskite usually needs specific atmospheres, especially controlled humidity. Here, we demonstrate the synthesis of compact methylammonium lead iodide perovskite (MAPbI3) on TiO2 under ambient conditions through one and two-step spin-coating deposition methods, which both resulted in an unconverted PbI2 on the films. The two-step method provided a higher amount of PbI2 regarding the reaction of methyl ammonium iodide (MAI) with an outer layer of the first bonded PbI2 hindered the inner layer to interact with MAI. The Ostwald ripening (OR) process that was applied to the thin film resulted through one-step deposition synthesis has successfully converted the unformed PbI2 to MAPbI3 with a more uniform, lower void, and higher crystal size as confirmed by XRD and SEM analysis results. The application of MAPbI3 prepared using OR treatment in the solar cell resulted in higher efficiency (7.64%) than the one synthesized without OR (4.91%). [ABSTRACT FROM AUTHOR]

In this work, we studied, at low temperature, the coherent evolution of the localized electron and hole spins in a polycrystalline film of CH3NH3PbI3 (MAPI) by using a picosecond-photo-induced Faraday rotation technique in an oblique magnetic field. We observed an unexpected anisotropy for the electron and hole spin. We determined the electron and hole Landé factors when the magnetic field was applied in the plane of the film and perpendicular to the exciting light, denoted as transverse ⊥   factors, and when the magnetic field was applied perpendicular to the film and parallel to the exciting light, denoted as parallel   ∥   factors. We obtained | g e , ⊥ | = 2.600   ±   0.004 , | g e , ∥ | = 1.604   ±   0.033 for the electron and | g h , ⊥ | = 0.406   ±   0.002 , | g h , ∥ | = 0.299   ±   0.007 for the hole. Possible origins of this anisotropy are discussed herein. [ABSTRACT FROM AUTHOR]

Controlling the crystallinity, homogeneity, and surface morphology is an efficient method of enhancing the perovskite layer. These improvements contribute toward the optimization of perovskite film morphology for its use in high-performance photovoltaic applications. Here, different solvents will be used in order to process the perovskite precursor, to improve the interfacial contacts through generating a smooth film and uniform crystal domains with large grains. The effect that the solvent has on the optical and structural properties of spin-coated methyl ammonium lead iodide (MAPbI3) perovskite thin films prepared using a single-step method was systematically investigated. The spin-coating parameters and precursor concentrations of MAI and PbI2 were optimized to produce uniform thin films using the different solvents N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL). The effect that the solvent has on the morphology of the MAPbI3 films was examined to determine how the materials can be structurally altered to make them highly efficient for use in perovskite hybrid photovoltaic applications. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results show that the synthesized MAPbI3 films prepared using DMSO, DMF, and GBL exhibit the best crystallinity and optical characteristics (photoluminescence (PL)), respectively, of the prepared films. The optical properties resulting from the noticeable improvement PL of the films can be clearly correlated with their crystallinity, depending on the solvents used in their preparation. The film prepared in DMSO shows the highest transmittance and the highest bandgap energy of the prepared films. [ABSTRACT FROM AUTHOR]

Under the framework of density functional theory (DFT) based on first principles, the local density approximation (LDA) and generalized gradient approximation (GGA) are used to analyze the phase‐transition pressure, band structure, density of states, atom populations, and bond populations of the five phases of CH3NH3PbI3. From the enthalpy of the five phases as a function of pressure, the 2H‐phase transforms into the O‐phase under 2 GPa, and the T‐phase transforms into the C‐phase under 0.3 GPa. The charge density and the charge population analysis show that methyl ammonia is connected by covalent bonds, and the PbI6 octahedron has both ionic and covalent bonds. As the pressure increases, the covalency of the CH and NH bonds in methyl ammonia decreases, while the covalency of the CN bond increases. From the charge density and the density of states, the 2H‐phase and 4H‐phase have indirect bandgaps, while C‐, O‐, and T‐phases have direct bandgaps. The valence band of CH3NH3PbI3 is mainly determined by the I‐5p and Pb‐6s orbitals, and the conduction band is mainly determined by the Pb‐6p orbitals. In addition, this study shows that the bandgap decreases with increasing pressure, and the ideal bandgap can be achieved by adjusting the pressure. [ABSTRACT FROM AUTHOR]

The nanowire and nanorod morphology offers great advantages for application in a range of optoelectronic devices, but these high-quality nanorod arrays are typically based on high temperature growth techniques. Here, we demonstrate the successful room temperature growth of a hybrid perovskite (CH3NH3PbBr3) nanorod array, and we also introduce a new low temperature anion exchange technique to convert the CH3NH3PbBr3 nanorod array into a CH3NH3PbI3 nanorod array while preserving morphology. We demonstrate the application of both these hybrid perovskite nanorod arrays for LEDs. This work highlights the potential utility of postsynthetic interconversion of hybrid perovskites for nanostructured optoelectronic devices such as LEDs, which enables new strategies for the application of hybrid perovskites.

The scientific community focused on finding environmentally safe alternative metal halides to address the instability and toxicity associated with lead perovskite materials. These alternatives are supposed to replace lead halides without altering the distinctive properties of lead perovskite materials. Additionally, they should contribute to producing longer-lasting and stable perovskite in solar cells. This research presents a practical investigation of using tin- and lead-based composites in perovskite iodide solar cells with Titanium dioxide (TiO 2) and Copper oxide (CuO) as electron transport materials (ETM) and hole transport materials (HTM), respectively. The performance parameters of the perovskite solar cells (PSCs) are compared with those of lead-based and lead-free PSCs with the same charge transport layers of ETM and HTM, as well as compare the practical results with the software results of Solar Cell Capacitance Simulation (SCAPS) package. In this study, the performance of PSCs with an absorption layer ((CH 3 NH 3 PbI 3) t /(CH 3 NH 3 SnI 3) 1-t) was examined. The thickness of the perovskite layer is represented by (t), which can take the values(t = 1, 0.5, or 0) μm. The results of the laboratory study were compared to the performance of PSCs based on numerical analysis of SCAPS modeling. PSCs were prepared with a configuration structure (FTO/compact TiO 2 /(CH 3 NH 3 PbI 3) t /(CH 3 NH 3 SnI 3) 1-t /CuO/Cu-electrode). A tetragonal phase was obtained for perovskite materials CH 3 NH 3 PbI 3 and CH3NH3SnI3 with a direct optical energy gap estimated at (1.55 and 1.35) eV, respectively. The l-V curve of the prepared PSCs was studied, and the performance of the solar cells was examined under a light intensity of 100 mW/cm2. The power conversion efficiency, PCE, of the prepared solar cells, was (PCE = 2.9, 3.11, or 0.5) at (t = 1, 0.5, or 0)μm, respectively. A comparative analysis was also performed between the empirical performance of the manufactured PSCs and the theoretical results acquired by the SCAPS package software. • Due to the instability and toxicity of lead perovskite materials, the scientific community of solar cell applications is looking into alternative metal halides that are safe for the environment, can replace lead halides without changing the unique properties of lead perovskite materials, and result in stable, longer-life perovskite in the solar cells. • In this study, the performance of perovskite solar cells with an absorption layer ((CH3NH3PbI3)t/(CH3NH3SnI3)1-t) was examined. • Perovskite solar cells were prepared with a configuration structure (FTO/compact TiO2/(CH3NH3PbI3)t/(CH3NH3SnI3)1-t/CuO/Al-electrode). • A tetragonal phase was obtained for perovskite materials CH3NH3PbI3 and CH3NH3SnI3 with a direct optical energy gap estimated at 1.55 and 1.35 eV, respectively. • The l-V curve of the prepared perovskite solar cells was studied, and the performance of the solar cells was examined under a light intensity of 100 mW/cm2. • A comparative analysis was also performed between the empirical performance of the manufactured perovskite solar cells and the theoretical results acquired by the SCAPS package software. [ABSTRACT FROM AUTHOR]

Carbon-based Perovskite Solar Cells (C-PSCs) present a promising avenue for enhancing the stability and commercialization of PSCs. However, the power conversion efficiency (PCE) of C-PSCs still lags behind that of metal-based PSCs. In this study, La-BDC (La-MOF prepared by La3+ and ligand H 2 BDC) has successfully synthesized using a simple hydrothermal method and then directly introduced into CH 3 NH 3 PbI 3 (MAPbI 3) perovskite precursor solution to prepare perovskite/La-BDC heterojunction structure with remarkable properties in light absorption, hydrophobicity, and crystallinity. By incorporating this structure, the PCE of C-PSCs with an FTO/SnO 2 /MAPbI 3 /La-BDC/Carbon architecture was effectively enhanced. The presence of C O functional group in La-BDC effectively reduced interface defects while improving carrier separation efficiency, and successfully passivated the free Pb2+ ions within the perovskite. Remarkably, the La-BDC-based device achieved a superior PCE of 14.95%, surpassing the pristine device's PCE by an impressive margin of 20.37%. Moreover, even after a 31 days period of air storage (temperature range of 15–25℃, humidity range of 15–30%), the La-BDC-based devices maintained over 90% of the initial performance, demonstrating excellent stability. This study provides a facile and effective strategy for improving the PCE and stability of C-PSCs through implementing a La-BDC heterojunction structure， and provides a new idea for MOF materials in the field of PSCs. • Hydrothermal synthesis was used to create La-BDC MOF nanocomposites. • Light absorption and hydrophobic qualities were improved by adding La-BDC. • C O group in La-BDC passivates free Pb2+ ions and reduces interface defects. • C-PSCs with La-BDC achieved an efficiency increase of over 20.37%. • The La-BDC-based device maintained more than 90% of its initial performance. [ABSTRACT FROM AUTHOR]

The research on organic-inorganic hybrid halide perovskites in the field of optoelectronics has greatly advanced the field of photodetection. However, the reported heterojunction structure of perovskite results in complex preparation processes. A simple method was designed to enhance the performance of CH 3 NH 3 PbI 3 flexible photodetector (PD) by optimizing the depletion width based on the piezo-phototronic effect. Under 5 V bias conditions, when the electrode width of PD is 3, 5, and 8 μm, where the response peaks at 760 nm are 0.06, 0.02, and 0.01 A/W, respectively. This depends on the decrease of electrode width and the increase of depletion width. As the strain increases, the PD response of the interdigital electrode at 3 μm increases from 0.020 to 0.0482 A/W. When the strain is 0.3, the responsiveness increases by 240 %. As the strain increases, the PD response of the interdigital electrode at 5 μm increases from 0.010 to 0.0255 A/W and the PD response of the interdigital electrode at 8 μm increases from 0.006 to 0.0137 A/W. Therefore, devices with a wide depletion width have significant performance advantages. This work improves the responsivity of perovskite flexible PD based on the piezo-phototronic effect by optimizing the depletion width, providing a simple and effective method for manufacturing perovskite thin film devices on high-performance flexible substrates. • Improving the performance of photodetectors by changing the depletion width. • The piezoelectric charge generated by the piezo-phototroniceffect widens the depletion layer width and improves the performance of the photodetector. • Mechanistically explained the optimization of depletion zone width to improve the performance of CH 3 NH 3 PbI 3 photodetectors. [ABSTRACT FROM AUTHOR]

[Display omitted] • FMIPs were prepared by selecting PFEA as a functional monomer. • FMIPs were employed for the functionalization of CH 3 NH 3 PbI 3 @CNDs. • FMIPs endowed perovskite with good selectivity, stability, and photoelectric property. • A novel cholesterol PEC sensor was developed based on FMIPs@CH 3 NH 3 PbI 3 @CNDs. • The new sensor has been successfully applied to cholesterol detection in human serum. Herein, a novel ultrasensitive cholesterol photoelectrochemical (PEC) sensor was designed based on fluorinated molecularly imprinted polymers (FMIPs) functionalized CH 3 NH 3 PbI 3 @carbon nanodots (CH 3 NH 3 PbI 3 @CNDs) platform. 2-(Perfluorooctyl) ethyl acrylate (PFEA), a functional monomer, was chosen not only to endow CH 3 NH 3 PbI 3 good selectivity but also improve its aqueous stability because of the fluorine containing long hydrophobic chain. Furthermore, the FMIPs can inhibit the recombination of electron holes and prolonged the carrier life time, and dramatically enhance the charge transfer efficiency by the reduction of defect density through the polymer passivation of grain boundaries of perovskite. The morphology, the enhanced hydrophobicity and photoelectric properties of FMIPs@CH 3 NH 3 PbI 3 @CNDs interface was characterized by transmission electron microscopy, Fourier transform infrared spectrum, scanning electron microscope, contact angle, photoluminescence spectrum and intensity modulated photovoltage spectrum, respectively. Under the optimized conditions, the linear range of the designed PEC sensor for cholesterol detection was 1.0 × 10−13–1.0 × 10−9 mol/L, and the detection limit was down to 8.9 × 10−14 mol/L. The new PEC sensor exhibited specific selectivity, good stability and hypersensitivity, and was successfully applied to cholesterol detection in human serum samples. This work extended the development of the MIPs based sensor and the high-performance perovskite. [ABSTRACT FROM AUTHOR]

Indoor photovoltaics (IPVs) are receiving great research attention recently due to their projected application in the huge technology field of Internet of Things (IoT). Among the various existing photovoltaic technologies such as silicon, Cadmium Telluride (CdTe), Copper Indium Gallium Selenide (CIGS), organic photovoltaics, and halide perovskites, the latter are identified as the most promising for indoor light harvesting. This suitability is mainly due to its composition tuning adaptability to engineer the bandgap to match the indoor light spectrum and exceptional optoelectronic properties. Here, in this review, we are summarizing the state-of-the-art research efforts on halide perovskite-based indoor photovoltaics, the effect of composition tuning, and the selection of various functional layer and device architecture onto their power conversion efficiency. We also highlight some of the challenges to be addressed before these halide perovskite IPVs are commercialized.

CH3NH3PbI3 is one of the most widely studied and most promising photoelectric conversion materials for large-scale application. However, once it is discharged into the aquatic environment, it will release a variety of lethal substances to the aquatic organisms. Herein, two typical aquatic pollution indicators, Scenedesmus obliquus (a typical phytoplankton) and Daphnia magna (a typical zooplankton), were used to assess the acute effects of CH3NH3PbI3 perovskite on aquatic organisms. The results showed that, when the initial CH3NH3PbI3 perovskite level (CPL) was 40 mg L−1 or higher, the growth of S. obliquus would be remarkably inhibited with significant decreases of chlorophyll content and protein content. And when the CPL was over 5 mg L−1, the survival of D. magna would be notably threatened. Specifically, the 72 h EC-50 of CH3NH3PbI3 perovskite to S. obliquus was calculated as 37.21 mg L−1, and the 24 h LC-50 of this perovskite to D. magna adults and neonates were calculated as 37.53 mg L−1 and 18.55 mg L−1, respectively. Moreover, remarkably solution pH declination and large amounts of lead bio-accumulation was observed in the both acute experiments, which could be the main reasons causing the above acute effects. Considering the strong acute effects of these CH3NH3PbI3 perovskite materials and their attractive application prospect, more attentions should be paid on their harmness to the environment.

Abstract In this study, the perovskite layers were prepared by two-step wet process with different CH3NH3I (MAI) concentrations. The cell structure was glass/FTO/TiO2-mesoporous/CH3NH3PbI3 (MAPbI3)/spiro-OMeTAD/Ag. The MAPbI3 perovskite films were prepared using high and low MAI concentrations in a two-step process. The perovskite films were optimized at different spin coating speed and different annealing temperatures to enhance the power conversion efficiency (PCE) of perovskite solar cells. The PCE of the resulting device based on the different perovskite morphologies was discussed. The PCE of the best cell was up to 17.42%, open circuit voltage of 0.97 V, short current density of 24.06 mA/cm2, and fill factor of 0.747.

In general, self-powered photodetectors are tedious and costly. Here, high-performance self-powered visible photodetectors based on MAPbI3 films were fabricated by using asymmetric Au electrodes. For this construction of photodetector, the illumination passing through the translucent MAPbI3 film can reduce the Schottky barrier between the lower electrode and perovskite, and the Au particles doping into the MAPbI3 at the contact areas between the upper electrode and films can also change the Schottky barrier, which leads to the formation of built-in potential. Without an applied bias, the photodetectors exhibit an ultralow dark current of ~ 3 pA. At the power intensity of 2.92 mW/cm2 under 635 nm illumination, a decent responsivity of 10 mAW−1, a high specific detectivity of 3.3 × 1011 cmHz1/2W−1, and an external quantum efficiency of 2.1% are obtained. The on/off ratio reaches 104 and the response speed is less than 50 ms. Our results pave a new design concept to form a self-powered perovskite-based photodetector. [ABSTRACT FROM AUTHOR]

Simulation studies are vital to understanding solar cell performance and in optimal device design for high-efficiency solar cells. Cell performance is sensitive to many factors, including device architecture, energy band alignment at the interfaces, materials used for photogeneration, charge extraction, doping density and thickness of various layers. The role of electron transport layer (ETL) thickness and its doping density on device performance is explored in this work. As the ETL thickness is increased from 10 nm to 200 nm, both fill factor (FF) and efficiency remain high up to 40 nm, at 0.85 and 28.04%, respectively, and beyond 40 nm, they decrease gradually due to a sharp increase in series resistance, reaching zero at 200 nm. However, Jsc and Voc remained unchanged up to an ETL thickness of about 150 nm and 160 nm, respectively. These results were confirmed by contour plots of the simulated Voc, Jsc, FF and efficiency results. We observed that when ETL approached 200 nm, Jsc and Voc decreased to zero and 0.88 V, respectively. This can be attributed to very high series resistance and recombination in the cell. Donor concentration variation in the ETL from 1017/cm3 to 1020/cm3 has much less impact on Jsc, and Voc remains unchanged. However, fill factor and efficiency improved, which might be due to an increase in conductivity in the ETL. Our result shows that for an optimized device, with an AM 1.5 spectrum, a cell efficiency of 29.64% was achieved with Voc, Jsc and fill factor of 1.241 V, 28.70 mA/cm2 and 0.83, respectively. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskite memristors with high resistive‐switching (RS) reliability and low power consumption are crucial for high‐density storage and high‐efficiency neuromorphic computing. However, the current overshoot in the electroforming process generally induces overgrowth of conductive filaments (CFs) and degrades the RS performance. Here, a simple photo‐assisted electroforming (PAE) method to suppress the current overshoot, in which the visible light irradiation is introduced into the initial electroforming process, is proposed for the first time. As a result, a reliable memristor with reduced RS fluctuation and enhanced cycling endurance is obtained, and also, the low operating current of 0.06 mA and low powerconsumption of 0.12 mW are achieved, which are about one order of magnitude lower than those of most reported hybrid perovskite‐based memristors. Further experimental evidence indicates that light irradiation plays dual roles: 1) the light‐induced lowering of iodide migration barrier leads to a significant reduction of overshoot current and forming voltage; 2) the enhanced local photoconductivity of the perovskite film shares the overshoot current through the CFs. Both factors limit the total quantity of vacancy defects generated in the electroforming process, thus preventing undesirable overgrowth of the CFs. The present PAE strategy has promise for developing high‐performance memristors. [ABSTRACT FROM AUTHOR]

Methylammonium lead iodide perovskite, CH 3 NH 3 PbI 3 (MAPbI 3) is a highly promising photovoltaic material, whose structural and electronic properties are very sensitive to applied stresses. Here, we show that the phase stability of a MAPbI 3 crystal can be controlled by structural defects and strains. We synthesized a single crystal of MAPbI 3 and measured its electrical properties across two successive structural phase transitions under applied pressure up to 4–9 GPa under multiple high-pressure cycling. We revealed three types of effects of this high-pressure treatment. (i) An increasing the level of defects and strains in the crystal greatly delays the first reconstructive phase transition, conserving the ambient-pressure tetragonal phase up to a record pressure of ∼1.4 GPa, much higher compared to its typical stability range of up to 0.3–0.5 GPa only. (ii) A time exposure of the crystal at a fixed pressure corresponding to the beginning of the second phase transition to a "destabilized" structure eliminated some of defects and strains; it down-shifted the phase boundaries back. (iii) A recrystallization of the sample after pressure-induced amorphization enhanced its structural stability against amorphization upon subsequent pressurization cycle. We proposed that the most abundant defects and strains, which could appear in the pressure-cycled MAPbI 3 crystals, were related to migration of iodine atoms from their regular sites to the MA interstices. Temperature-dependent photoluminescence measurements indicated that the sample recovered after the high-pressure cycling crystallized back into the initial tetragonal crystal structure. Whereas, its stability range expanded toward lower temperatures by 20 K and a band gap slightly increased, from 1.59 to 1.625 eV (at 290 K). Using this organic-inorganic perovskite as an example, we show how the phase stability of such materials can be manipulated by creation and elimination of structural defects and local strains. [Display omitted] • The electrical properties of the MAPbI 3 under high-pressure cycling up to 4–9 GPa. • The phase stability of MAPbI 3 can be controlled by structural defects and strains. • Conservation the initial tetragonal phase up to a record pressure of ∼1.4 GPa. • A recrystallization of MAPbI 3 enhances structural stability against amorphization. [ABSTRACT FROM AUTHOR]

Two organic-inorganic halide CH3NH3PbI3 perovskite solar cells prepared in the same experimental batch but having different power conversion efficiencies −18.46% and 17.15%—were investigated based on the absolute electroluminescence (EL) efficiency measurements and traditional I-V measurements. The possible factors that affect the power conversion efficiency were also investigated. Comparing the experimental I-V curves of the two solar cells, it was found that the short-circuit currents (Jsc) were nearly the same; however, the open-circuit voltages (Voc) were markedly different. Moreover, the deduced I-V curves from the absolute EL efficiencies of the two solar cells, which were mainly affected by the material quality, were almost the same, proving that the device processing technology has a vital effect on Voc.

Most digital information today is encoded in the magnetization of ferromagnetic domains. The demand for ever-increasing storage space fuels continuous research for energy-efficient manipulation of magnetism at smaller and smaller length scales. Writing a bit is usually achieved by rotating the magnetization of domains of the magnetic medium, which relies on effective magnetic fields. An alternative approach is to change the magnetic state directly by acting on the interaction between magnetic moments. Correlated oxides are ideal materials for this because the effects of a small external control parameter are amplified by the electronic correlations. Here, we present a radical method for reversible, light-induced tuning of ferromagnetism at room temperature using a halide perovskite/oxide perovskite heterostructure. We demonstrate that photoinduced charge carriers from the CH3NH3PbI3 photovoltaic perovskite efficiently dope the thin La0:7Sr0:3MnO3 film and decrease the magnetization of the ferromagnetic state, allowing rapid rewriting of the magnetic bit. This manipulation could be accomplished at room temperature; hence this opens avenues for magnetooptical memory devices. [ABSTRACT FROM AUTHOR]

From application point of view, scalable, facile and rapid synthesis method for mass production of a homogeneous and phase pure CH3NH3PbI3 micron size crystal at the industry level is still highly required, although it has been claimed that the CH3NH3PbI3 crystals can be prepared by solution‐annealing the precursors at elevated temperature or prolonged reaction time. Herein, polycrystalline CH3NH3PbI3 micron size crystals can be prepared by reactive crystallization of PbI2 and CH3NH3I in a stoichiometric ratio at room temperature. TXM (Transmission X‐ray Microscopy), optical microscope, TEM and TEM‐EDX analysis were used to confirm the nature of the CH3NH3PbI3 product. Moreover, Ostwald ripening of iodide ion into PbI2 is proposed as the key step to form 3D PbI3−, followed by the intercalation of CH3NH3+ for this reactive crystallization. Interestingly, this result suggests that industry level mass production of micron CH3NH3PbI3 crystals is possible with this novel synthesis method. [ABSTRACT FROM AUTHOR]