Perovskite (structure)

About: Perovskite (structure) is a research topic. Over the lifetime, 51482 publications have been published within this topic receiving 1541750 citations.

Ferroelectric La‐Sr‐Co‐O/Pb‐Zr‐Ti‐O/La‐Sr‐Co‐O heterostructures on silicon via template growth

Abstract: Ferroelectric Pb0.9La0.1Zr0.2Ti0.8O3 thin film capacitors with a symmetrical La‐Sr‐Co‐O top and bottom electrodes have been grown on [001] Si with yttria stabilized zirconia (YSZ) buffer layer. A layered perovskite ‘‘template’’ layer (200–300 A thick), grown between the YSZ buffer layer and the bottom La‐Sr‐Co‐O electrode, is critical for obtaining the required orientation of the subsequent layers. When compared to the capacitors grown with the Y‐Ba‐Cu‐O top and bottom electrodes, these structures possess two advantages: (i) the growth temperatures are lower by 60–150 °C; (ii) the capacitors show a larger remnant polarization ΔP (ΔP=switched polarization–nonswitched polarization), 25–30 μC/cm2, for an applied voltage of only 2 V (applied field of 70 kV/cm). The fatigue, retention, and aging characteristics of these new structures are excellent.

High-Efficiency Solution-Processed Planar Perovskite Solar Cells with a Polymer Hole Transport Layer

Abstract: DOI: 10.1002/aenm.201401855 In this work we demonstrate a high-effi ciency solutionprocessed inverted CH 3 NH 3 PbI 3 perovskite solar cell, which is free of PEDOT:PSS and high-temperature processed metal oxides ( Figure 1 a). We use poly[ N , N ′-bis(4-butylphenyl)N , N ′bis(phenyl)benzidine] (poly-TPD) as the HTL and electron blocking layer for the perovskite cells. In previous reports, polyTPD was used as an HTL in vacuum deposited perovskite solar cells. [ 14 ] Here, the perovskite fi lm was formed by sequential deposition of lead iodide (PbI 2 ) and methyl ammonium iodide (CH 3 NH 3 I). We found that the resulting fi lm consisted of large crystallites with a complete coverage on the poly-TPD surface, and the average effi ciency of the fi nal devices reach a value of 13.8% and a maximum value as high as 15.3%. To deposit the perovskite fi lm on the poly-TPD surface, a concentrated solution of PbI 2 was fi rst spin-coated and then heated to partially evaporate the solvent and crystallize PbI 2 . Subsequently, a dilute solution of CH 3 NH 3 I is spin-coated on top of the PbI 2 layer and CH 3 NH 3 PbI 3 is formed by interdiffusion of the precursors. As shown in Figure 1 b, a composite layer of spin-coated [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 60 BM), and thermally evaporated C 60 and 2,9-dimethyl4,7-diphenyl-1,10-phenanthroline (BCP) is deposited on top of the CH 3 NH 3 PbI 3 layer to planarize the surface of the perovskite layer, and to facilitate electron extraction and hole blocking. [ 17 ]

High spectral resolution of gamma-rays at room temperature by perovskite CsPbBr3 single crystals

Abstract: Gamma-ray detection and spectroscopy is the quantitative determination of their energy spectra, and is of critical value and critically important in diverse technological and scientific fields. Here we report an improved melt growth method for cesium lead bromide and a special detector design with asymmetrical metal electrode configuration that leads to a high performance at room temperature. As-grown centimeter-sized crystals possess extremely low impurity levels (below 10 p.p.m. for total 69 elements) and detectors achieve 3.9% energy resolution for 122 keV 57Co gamma-ray and 3.8% for 662 keV 137Cs gamma-ray. Cesium lead bromide is unique among all gamma-ray detection materials in that its hole transport properties are responsible for the high performance. The superior mobility-lifetime product for holes (1.34 × 10−3 cm2 V−1) derives mainly from the record long hole carrier lifetime (over 25 μs). The easily scalable crystal growth and high-energy resolution, highlight cesium lead bromide as an exceptional next generation material for room temperature radiation detection. Detection and spectroscopic measurements of gamma-ray used to rely on expensive materials such as CdZnTe crystals. Here He et al. develop a melt method to grow large size CsPbBr3 perovskite crystals and the devices achieve low cost, high energy resolving capabilities and stability.

Freestanding crystalline oxide perovskites down to the monolayer limit

Abstract: Two-dimensional (2D) materials such as graphene and transition-metal dichalcogenides reveal the electronic phases that emerge when a bulk crystal is reduced to a monolayer1-4. Transition-metal oxide perovskites host a variety of correlated electronic phases5-12, so similar behaviour in monolayer materials based on transition-metal oxide perovskites would open the door to a rich spectrum of exotic 2D correlated phases that have not yet been explored. Here we report the fabrication of freestanding perovskite films with high crystalline quality almost down to a single unit cell. Using a recently developed method based on water-soluble Sr3Al2O6 as the sacrificial buffer layer13,14 we synthesize freestanding SrTiO3 and BiFeO3 ultrathin films by reactive molecular beam epitaxy and transfer them to diverse substrates, in particular crystalline silicon wafers and holey carbon films. We find that freestanding BiFeO3 films exhibit unexpected and giant tetragonality and polarization when approaching the 2D limit. Our results demonstrate the absence of a critical thickness for stabilizing the crystalline order in the freestanding ultrathin oxide films. The ability to synthesize and transfer crystalline freestanding perovskite films without any thickness limitation onto any desired substrate creates opportunities for research into 2D correlated phases and interfacial phenomena that have not previously been technically possible.

Titanium-carbide MXenes for work function and interface engineering in perovskite solar cells.

Abstract: To improve the efficiency of perovskite solar cells, careful device design and tailored interface engineering are needed to enhance optoelectronic properties and the charge extraction process at the selective electrodes. Here, we use two-dimensional transition metal carbides (MXene Ti3C2Tx) with various termination groups (Tx) to tune the work function (WF) of the perovskite absorber and the TiO2 electron transport layer (ETL), and to engineer the perovskite/ETL interface. Ultraviolet photoemission spectroscopy measurements and density functional theory calculations show that the addition of Ti3C2Tx to halide perovskite and TiO2 layers permits the tuning of the materials’ WFs without affecting other electronic properties. Moreover, the dipole induced by the Ti3C2Tx at the perovskite/ETL interface can be used to change the band alignment between these layers. The combined action of WF tuning and interface engineering can lead to substantial performance improvements in MXene-modified perovskite solar cells, as shown by the 26% increase of power conversion efficiency and hysteresis reduction with respect to reference cells without MXene. Addition of MXenes in the halide perovskite film, in the electron transport layer and at the interface between these layers is shown to enhance the efficiency of and reduce hysteresis in perovskite solar cells.