Organolead Halide Perovskite Research Articles

Recent advances in organolead halide crystalline materials for photocatalytic H2 evolution and CO2 reduction applications.

The photocatalytic technique has been widely recognized as a feasible technological route for sustainable energy conversion of solar energy into chemical energy. Photocatalysts play a vital role in the whole catalytic process. In particular, organolead halide perovskites have become emerging photocatalysts, owing to their precisely tunable light absorption range, high carrier diffusion mobility, and longer carrier lifetime and diffusion length. Nevertheless, their intrinsic structural instability and high carrier recombination rate are the major bottlenecks for further development in photocatalytic applications. This Frontier is focused on the recent research about the instability mechanism of organolead halide perovskites. Then, we summarize the recently developed strategies to improve the structural stability and photocatalytic activity of organolead halide materials, with an emphasis on the construction of organolead halide crystalline catalysts with high intrinsic structural stability. Finally, an outlook and challenges of organometal halide photocatalysts are presented, demonstrating the irreplaceable role of this class of emergent materials in the field of photo-energy conversion.

High performance self-powered photodetector based on CuBi2O4/MAPbI3 heterostructure

Methylammonium lead halide perovskites have garnered significant consideration for application in numerous optoelectronic devices due to their remarkable physical properties. However, the photoconductivity performance of these organolead halide perovskites is still lower than the conventional Si optoelectronic devices such as photodetectors, which is one of the major barriers to their practical applications. Combining suitable inorganic semiconductors with organolead halide perovskite may provide an alternative route for fabricating photodetectors that are expected to have improved photosensitivity. Here, a high performance self-power photodetector based on CuBi2O4/CH3NH3PbI3 (MAPbI3) heterojunction was synthesized under ambient conditions using the spin-coating technique. The severely reduced peak intensity in PL spectra and short decay time of CuBi2O4/MAPbI3 compared to MAPbI3 indicate efficient charge separation at the interface. The self-powered CuBi2O4/MAPbI3 showed photovoltaic-like effect with a maximum open circuit voltage Vo of ∼0.34 ± 0.02 V under the illumination of 365 nm light with 8.63 μW/cm2 power density. Moreover, CuBi2O4/MAPbI3 heterojunction base photodetector exhibits a high responsivity of ∼0.39 ± 0.04 W/A, a detectivity of ∼1.79 ± 0.17 × 1011 Jones, a fast response speed (rise time ∼ 36 ± 0.14 ms, fall time 81 ± 0.21 ms) and self-powering ability compared to that of MAPbI3 only device. This work offers an effective and feasible way to improve the performance of MAPbI3-based devices for photoelectronic applications.

Organolead halide perovskites: Synthetic routes, structural features, and their potential in the development of photovoltaic

Abstract About 13 TW of energy is needed to sustain the lifestyle of people worldwide but an additional 10 TW clean energy will be required by 2050. The increase in the world population and the demand for energy that rely on fossil fuels has resulted in global warming that necessitates the need for alternative energy such as solar. Solar energy is abundant and readily available, and its use will contribute to sustainable development. Metal halide perovskites are promising materials for the development of next-generation solar cells. The power conversion efficiency (PCE) of 25.8% obtained for organolead halide perovskite is close to the polycrystalline solar cell’s efficiency at 26.3% and these materials offer great prospects for future photovoltaic development. To approach the theoretical efficiency limit, it is very important to study the development of perovskite solar cells in terms of material composition, fabrication techniques, and device architectures with emphasis on charge transport layers and electrodes. Limitations to PCE and stability of perovskites, optoelectronic properties, lifetime and stability, wide-scale applications, components of the perovskites solar cell, the standard for testing conditions for good stability and its evolution into the lower layered perovskite solar cells were examined in the current review.

Insight into the interface engineering between methylammonium lead halide perovskites and gallium oxide: a first-principles approach.

Interface engineering of the organo-lead halide perovskite devices has shown the potential to improve their efficiency and stability. In this study, the atomic, electronic, optical and transport characteristics of MAPbI3/Ga2O3 and MAPbCl3/Ga2O3 interfaces were investigated by using first-principles calculations. Eight different interfacial models were established and the interfacial properties were discussed. The results show that the PbI/O configuration exhibits the largest bonding strength out of all eight interfacial configurations. Owing to the larger interfacial interaction, the charge transfer at the PbI/O interface is significantly more than that at the other interfaces. The analysis of absorption spectra indicates that the Ga-terminated perovskite/Ga2O3 heterostructures are expected to have great potential for efficient optoelectronic applications. The analysis of transmission spectra shows that the MA/O configurations with more transmission peaks near the Fermi level exhibit lower resistance compared to others. The results of our study could help understand the interfacial engineering mechanism between perovskite and Ga2O3.

(Invited, Digital Presentation) Carbon-Based Multi-Porous-Layered-Electrodes for Highly-Stable Perovskite Solar Cells for Space Application

Organo-lead halide perovskite solar cells (PSCs) have attracted the attention due to the high efficiency and the cost-effective manufacturing by printing system. However, PSCs have been unstable due to water from outside and iodide (I-) reacts with the back contact metal (Au or Ag) inside. To solve these two issues, porous-carbon-electrodes have been introduced in PSCs by a group of Hongwei Han. The MPLE-PSCs show very high stability: thermal stability at 100 ֩C over 4500 h in dark (by Univ. of Hyogo, Japan); damp-heat stability at 85 ֩C-85%RH over 3,000 h in dark (by Univ. of Hyogo and Kishu Giken Kogyo, Japan); light stability at 55 ֩C over 10,000 h (by EPFL, Switzerland). In this conference, we will show a challenging work of high thermal stability at 130 ֩C, which is required for outer space application.

(Invited, Digital Presentation) Carbon-Based Multi-Porous-Layered-Electrodes for Highly-Stable Perovskite Solar Cells for Space Application

Organo-lead halide perovskite solar cells (PSCs) have attracted the attention due to the high efficiency and the cost-effective manufacturing by printing system. However, PSCs have been unstable due to water from outside and iodide (I-) reacts with the back contact metal (Au or Ag) inside. To solve these two issues, porous-carbon-electrodes have been introduced in PSCs. We are showing a challenging work of high thermal stability at 100-140 ֩C in vacuum, which is required for outer space application.

The Potential Effect of Annealing Mesostructured Titanium Dioxide Electrode in a Closed Box Furnace on the Concentration of Lead (II) Iodide Solution Required for Optimal Performance of Mesoscopic Perovskite Solar Cells

Highly reproducible mesoscopic perovskite solar cells (PSCs) can be fabricated using two-step sequential deposition of organo-lead halide (perovskite) active layer. However, differences in the processing conditions of individual layers which are subsequently assembled to construct the ultimate device can result in variations in the solar cell performance. For instance, here we report trends in the device performance as a function of PbI2 solution concentration, where the compact and mesoporous TiO2 layers were annealed in a closed box furnace (instead of doing it in open air). We observed that the devices prepared using 1.2 M PbI2 solution concentration performed better than those prepared from 0.8 M and 1 M PbI2 solutions. Generally, the researchers use the hot plate in an open-air environment or use a special hot plate where a continuous flow of air is ensured while annealing TiO2 electron selective layers (ESL) for perovskite solar cells. In this case, the highest possible device efficiencies are achieved using 1 M concentration of PbI2 solution. Although the influence of PbI2 solution concentration has been previously studied in detail, here our prime focus is to briefly comment on slight differences in the device performance trends which we observed in comparison to the previously reported results, where TiO2 layers were calcined in open air.

Imaging the Moisture-Induced Degradation Process of 2D Organolead Halide Perovskites.

Two-dimensional (2D) and quasi-2D Ruddlesden–Popper (RP) phase organolead halide perovskites are promising materials for both photovoltaic and optoelectronic devices. Although they are known to be more stable when exposed to moisture than their 3D counterpart, chemical degradation of these materials under moisture, which not only leads to a significant drop in device performance but also leads to lead leakage, yet remains one of the most serious hurdles for their practical applications. To gain insight into the degradation mechanism of 2D/quasi-2D perovskites under moisture conditions, the degradation pathway of 2D/quasi-2D (PEA)2(MA)n−1PbnI3n+1 (PEA = C6H5C2H4NH3+, MA = CH3NH3+, and n is the number of perovskite layers between adjacent organic spacer layers) perovskite single crystals (SCs) and thin film are explored. We observe the degradation process by mapping the photoluminescence of the 2D perovskites and demonstrate that the larger-n phases all directly degrade into the relative stable n = 1 phase and MAI and PbI2, which is a mechanism different from that in previous reports and further confirmed in the 2D perovskite thin film. This degradation process is also found to be independent of the boundary and morphology of the SCs. This discovery provides a new perspective for understanding the chemical degradation of the 2D perovskite materials and may inspire new solutions for improving their moisture stability.

Difluorobenzylamine Treatment of Organolead Halide Perovskite Boosts the High Efficiency and Stability of Photovoltaic Cells.

As one of the most competitive light-harvesting materials, organometal halide perovskites have attracted great attention due to their low-cost and top-down solution fabricability. However, the instability of perovskites in a moist environment reduces the potential for their commercialization. In this study, novel 2,4-fluorobenzylamine (FBA) was employed as the passivation material, which could successfully suppress the defects and improve the moisture resistance of perovskites, resulting in an ultrahigh power conversion efficiency of 17.6% for the carbon-based perovskite solar cells with good stability. Meanwhile, the whole process of interactions between the H2O molecule and the perovskite lattice was first elucidated by density functional theory calculations, which demonstrated the underlying mechanism of the improvement of moisture stability with the FBA treatment. This work opens up a new route toward addressing the main obstacles in the practical application of perovskite devices under ambient conditions.

Continuous-flow synthesis of ultrahigh luminescent perovskite nanocrystals using forced thin film reactor and application for light-emitting diodes

Owing to their excellent optical properties, organolead halide perovskite nanocrystals (PeNCs) have gained significant attention. Considering their industrial contribution, exploring practical production of high-quality PeNCs is of major importance. In this work, we demonstrate continuous-flow synthesis of ultrahigh luminescent PeNCs with high color purity using a forced thin film reactor. We successfully demonstrate the effectiveness of this reactor as a crystal growth environment. The photoluminescence quantum yields were improved to 94% as a result of the unique mixing process. After film formation, this reactor enabled the application for perovskite light-emitting diodes.

Extended air, light, and heat-resistive organolead halide perovskite single-crystalline microrods for high-performance photodetectors

Two-dimensional organic–inorganic hybrid perovskites are much attracted due to promising stable optoelectronic properties with tunable quantum well structures.

Soft Polymer-Organolead Halide Perovskite Films for Highly Stretchable and Durable Photodetectors with Pt-Au Nanochain-Based Electrodes.

The rigid and brittle nature of methylammonium lead iodide (MAPbI3) polycrystalline films limits their application in stretchable devices due to rapid deterioration in performance on cycling. By incorporation of polymer chains in the MAPbI3 films, a strategy to alter the mechanical modulus and the viscoelastic nature of the films has been developed. Combining this with flexible nanochain electrodes, highly stretchable and stable perovskite devices have been fabricated. The resultant polymer-MAPbI3 photodetector exhibits ultralow dark currents (∼10-11 A) and high light switching ratios (∼103) and maintains 75% of performance after 30 days. The viscoelastic nature and lower modulus of the polymer improve the energy dissipation in the polymer-MAPbI3 devices; as a result, they maintain 52% of the device performance after 10000 stretching cycles at 50% strain. The difference in the mechanical behavior is clearly observed in the failure mode of the two films. While rapid catastrophic cracking is observed in MAPbI3 films, the intensity and size of such crack formation are highly limited in polymer-MAPbI3 films, which prevent their failure.

(Invited) Vacuum Deposition and Crystal Growth of Organolead Halide Perovskite

Perovskite solar cells are developing very rapidly and have attracted much attention because of their high power-conversion efficiencies (PCE). Fabrication control of perovskite crystal is important because the reproducibility of the device performance is important issue for perovskite solar cells. We have been focusing on vacuum deposition for the precise control of the fabrication of perovskite. We demonstrated that laser deposition method is useful for the precise deposition-rate control of methylamine iodide[1], where its high vapor pressure makes it difficult to control its deposition rate by conventional deposition method. By taking the advantage of deposition control, we focused on the crystal growth and crystal-growth analysis of perovskite. In this paper, the technical aspects of laser deposition method will be addressed, followed by fabrication of perovskite solar cells [1], epitaxial growth [2] and growth dynamics analysis using laser deposition method.Firstly, we implemented laser deposition for the deposition of perovskite, where the source materials (PbI2, CH3NH3I) were heated with the IR continuous-wave laser. The PID control system was implemented to adjust the deposition rate and the stabilized evaporation rate was achieved. Perovskite solar cells were constructed using the cell structure of ITO/PEDOT:PSS/NiOx/PCDTBT/CH3NH3PbI3/PCBM/BCP/Al and power conversion efficiency of 16% was obtained.Next, we attempted epitaxial growth of CH3NH3PbI3 on (1 0 0) oriented rubrene single crystals to obtain highly ordered perovskite crystal. We succeeded in the epitaxial growth of perovskite both by a co-deposition method and an alternative deposition method. The precise crystal orientation and crystallization dynamics were analyzed using grazing incident wide angle X-ray scattering (GIWAXS) at a synchrotron radiation facility (SPring-8, BL46XU).

Self-powered narrowband visible-light photodetection enabled by organolead halide perovskite CH3NH3PbBr3/p-Si heterojunction

In this work, we have reported self-powered narrowband visible-light photodetectors based on organolead halide perovskite CH3NH3PbBr3 (MAPbBr3)/p-Si heterojunctions, which were prepared by growing MAPbBr3 microcrystals on the p-Si substrate using a room-temperature antisolvent-assisted crystallization method. Morphological, structural, and optical investigations showed that the as-grown MAPbBr3 microcrystals possessed a high crystalline quality. Electrical characterizations showed that the hetero-pn junction was formed within the MAPbBr3/p-Si heterojunction. Thanks to the high crystalline quality of MAPbBr3 microcrystals, the as-fabricated heterojunction photodetectors operating under a bias voltage of 0 V exhibited a high on–off ratio of ∼5.3 × 105, a narrow photosensitivity spectrum with the full width at half maximum of 18.2 nm, a high photoresponse speed with the rising/falling time of 115.7/53.4 ms, and excellent stability to visible-light signals. Finally, the photodetection mechanism was proposed. It showed that the observed narrowband photodetection was attributed to the self-filtering effect caused by the thick MAPbBr3 microcrystals. The results presented in this work will provide valuable strategies for the fabrication of self-powered narrowband visible-light photodetectors in the future.

Investigating the effect of applied bias on methylammonium lead iodide perovskite by electrical and positron annihilation spectroscopic studies

The formation of point defects in the crystal lattice of organic–inorganic hybrid perovskites is detrimental to the long-term stability of the perovskite-based solar cell. The observed hysteresis in organolead halide perovskite solar cell during the photocurrent measurement is believed to be the consequence of such defect sites. In the present work, we are reporting the formation of reversible and/or irreversible lattice defects in methylammonium lead iodide perovskite depending on the magnitude of bias voltage studied by electrical measurements and positron annihilation spectroscopy (PAS). Current vs voltage (I–V) measurements support the formation of p/n junction at the metal/semiconductor interfaces, suggesting the defects-driven ion migration under the applied bias. In-situ PAS has elucidated the nature of vacancy sites formed due to the application of bias voltage. In the lower biased voltage (<1 V), the formation of lattice defects is reversible, while beyond a threshold voltage of 1.2 V, the defects become permanent as observed by the PAS.

Nanoscale Architecture of Polymer-Organolead Halide Perovskite Films and the Effect of Polymer Chain Mobility on Device Performance.

The integration of polymer chains with organolead halide perovskite (MAPbI3) films, leading to enhanced stability and electro-optical performance, is critically affected by the molecular weight of chains. The molecular weight determines the mobility and volume of the chains, which affects the crystallization kinetics and, hence, perovskite grain size. The insulating nature of the chains is another critical factor that affects both ion migration and conduction of electronic charge. The combined effect of these factors leads to optimal performance with the use of medium-length chains. A simple model integrating the two effects accurately fits the response of the polymer-perovskite composite. Further characterization results show that the polymer-perovskite films have a three-layer architecture consisting of nanoscale polymer-rich top and bottom layers. These combined results show that the optimization of performance in polymer-perovskite devices depends critically on the size of the chains due to their multiple effects on the perovskite matrix.

The effect of bromide precursor on the properties of organolead halide perovskite for solar cell fabricated under ambient condition

Hybrid CH3NH3PbI3 − xBrx have drawn a tremendous interest as light harvesters in mesoscopic and planar heterojunction solar cells due to their high coefficient absorption. Herein, we investigated the difference between the effect of different bromide precursor on the properties of prepared CH3NH3PbI3 − xBrx thin film. In this study, the CH3NH3PbI3 − xBrx perovskite films were made by two processes. The first process consist in adding PbBr2 in the PbI2 with different molar ratios (x = 0, 0.05, 0.1) followed by depositing MAI in isopropanol. The second process resides in depositing CH3N3Br in isopropanol on the top of PbI2 − xBrx followed by dropping a solution of MAI in isopropanol. The study revealed that the prepared thin film using the first process with molar ratio 0.05 exhibited high crystallinity, suitable morphology, high absorption with non-radiative recombination. These attractive properties of the thin film prepared by the first process should heighten interest in its use as a solar absorber layer for increasing of solar cells efficiency.

Organolead halide perovskites beyond solar cells: self-powered devices and the associated progress and challenges

Applications of self-driven optoelectronic devices based on a wide array of organolead halide perovskites.

High-performance perovskite photodetectors based on CH3NH3PbBr3 quantum dot/TiO2 heterojunction

Organo-lead halide perovskite materials have opened up a great opportunity to develop high performance photodetectors because of their superior optoelectronic properties. The main issue with perovskite-only photodetector is severe carrier recombination. Integration of perovskite with high-conductive materials such as graphene or transition metal sulfides certainly improved the photoresponsivity. However, achieving high overall performance remains a challenge. Here, an improved photodetector is constructed by perovskite quantum dots (QDs) and atomic layer deposited ultrathin TiO2 films. The designed CH3NH3PbBr3 QD/TiO2 bilayer device displays inclusive performance with on/off ratio of 6.3 × 102, responsivity of 85 A W−1, and rise/decay time of 0.09/0.11 s. Furthermore, we demonstrate that interface plays a crucial role in determining the device current and enhance the overall performance of heterostructure photodetector through interface engineering. We believe that this work can provide a strategy to accelerate development of high-performance solution-processed perovskite photodetectors.

Recent advances in resistive random access memory based on lead halide perovskite

AbstractLead halide perovskites have attracted increasing attention in photovoltaic devices, light‐emitting diodes, photodetectors, and other fields due to their excellent properties. Besides optoelectronic devices, growing numbers of studies have focused on the perovskite‐based electrical devices in the past few years, such as transistors and resistive random access memories (RRAMs). Here, this article summarizes the recent progress the researchers have made of RRAM devices. Primarily, the working mechanism and the key parameters of RRAM are introduced. Generally, the working principles, including the conductive filament model (containing the types of the model of the metal cations‐induced filament and the model of the ions migration in bulk), the interface effect, and the electronic effect are the origins of the RRAM behaviors, and hence, various factors that affect the device performance are explored. Then, RRAMs based on organolead halide perovskite and all‐inorganic perovskite are discussed in terms of different structures, different compositions, and different fabrication methods. Finally, a brief conclusion and a broad outlook are given on the progress and challenges in the field of perovskite‐based RRAMs.image