Search results for "PEROVSKITE"
showing 10 items of 458 documents
Boosting Long-Term Stability of Pure Formamidinium Perovskite Solar Cells by Ambient Air Additive Assisted Fabrication
2021
Due to the high industrial interest for perovskite-based photovoltaic devices, there is an urgent need to fabricate them under ambient atmosphere, not limited to low relative humidity (RH) conditions. The formamidinium lead iodide (FAPI) perovskite α-black phase is not stable at room temperature and is challenging to stabilize in an ambient environment. In this work, we show that pure FAPI perovskite solar cells (PSCs) have a dramatic increase of device long-term stability when prepared under ambient air compared to FAPI PSCs made under nitrogen, both fabricated with N-methylpyrrolidone (NMP). The T80 parameter, the time in which the efficiency drops to 80% of the initial value, increases f…
Doping induced stable room temperature dual emission from gadolinium doped vacancy ordered double halide perovskite, Gd:Cs2SnCl6
2022
The recent advancement in bandgap engineering through controlled doping has widen the prospectof vacancy ordered double halide perovskites (VO DHPs) by conferring them with designableoptoelectronic properties. Here, we report synthesis of Gd doped Cs2SnCl6 via a simplesolvothermal method. Gd3+ ions doping lowers the band gap from 3.8 eV to 2.8 eV and facilitatesstable room temperature dual PL emission centered at 440 nm and 610 nm. The macroscopicemission process is well supported by the confocal PL emission studies on isolated crystallites.Both the pristine (Cs2SnCl6) and Gd:Cs2SnCl6 exhibit crystalline cubic structure with Fm3m spacegroup. Rietveld refinement correlates well with the cubi…
Preparation and characterisation of optical and optoelectronic devices based in two-dimensional semiconductors
2020
In the Materials Science field, two-dimensional materials have gained the scientific community attention in recent years. The change and the appearance of novel properties when their thickness is reduced to nanometric scale has special interest for its fundamental properties study for, from this base, the design and its implementation in devices. The wide variety of materials with the possibility of being exfoliated at the two-dimensional level opens the field to different applications, from optoelectronic devices, detection and sensing, energy storage, catalysis, medical applications and quantum information technologies, among others. This thesis gathers results in both directions: a funda…
Ligand-Length Modification in CsPbBr3 Perovskite Nanocrystals and Bilayers with PbS Quantum Dots for Improved Photodetection Performance
2020
Nanocrystals surface chemistry engineering offers a direct approach to tune charge carrier dynamics in nanocrystals-based photodetectors. For this purpose, we have investigated the effects of altering the surface chemistry of thin films of CsPbBr3 perovskite nanocrystals produced by the doctor blading technique, via solid state ligand-exchange using 3-mercaptopropionic acid (MPA). The electrical and electro-optical properties of photovoltaic and photoconductor devices were improved after the MPA ligand exchange, mainly because of a mobility increase up to 5 ×
Solid-state compatibility of Ca:LaNbO4 with perovskite cathodes: Evidences from X-ray microspectroscopy
2022
The solid-state compatibility between calcium-doped lanthanum niobate and three perovskite cathode materials was investigated using two X-ray microbeam techniques, micro X-ray fluorescence and micro X-ray absorption spectroscopy. The cathode powders (lanthanum strontium ferrite, either cobalt or copper-doped, and lanthanum strontium cobaltite) in contact with the dense electrolyte pellet were annealed at 1150 degrees C for 12-144 h to simulate the effect of thermal stresses due to fabrication and long-term operation. As a result, several interdiffusion phenomena were then observed on the bilayer cross-sections: in particular, the chemical state and coordination environment of calcium, iron,…
In situ transmission electron microscopy study of electron beam-induced transformations in colloidal cesium lead halide perovskite nanocrystals
2017
An increasing number of studies have recently reported the rapid degradation of hybrid and all-inorganic lead halide perovskite nanocrystals under electron beam irradiation in the transmission electron microscope, with the formation of nanometer size, high contrast particles. The nature of these nanoparticles and the involved transformations in the perovskite nanocrystals are still a matter of debate. Herein, we have studied the effects of high energy (80/200 keV) electron irradiation on colloidal cesium lead bromide (CsPbBr3) nanocrystals with different shapes and sizes, especially 3 nm thick nanosheets, a morphology that facilitated the analysis of the various ongoing processes. Our resul…
Efficient Monolithic Perovskite/Perovskite Tandem Solar Cells
2016
Thin-film solar cells suffer from various types of recombination, of which leakage current usually dominates at lower voltages. Herein, we demonstrate first a three-order reduction of the shunt loss mechanism in planar methylammonium lead iodide perovskite solar cells by replacing the commonly used hole transport layer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with a better hole-selective polyarylamine. As a result, these cells exhibit superior operation under reduced light conditions, which we demonstrate for the extreme case of moonlight irradiance, at which open-circuit voltages of 530 mV can still be obtained. By the shunt removal we also observe the VOC to dro…
Solid-state NMR characterization of the structure and thermal stability of hybrid organic-inorganic compounds based on a HLaNb2O7 Dion-Jacobson layer…
2016
Dion-Jacobson phases, like MLaNb2O7, are an interesting class of ion-exchangeable layered perovskites possessing electronic and photocatalytic properties. Their protonated and organo-modified homologues, in particular, have already been indicated as promising catalysts. However, the structural analysis of these highly tailorable materials is still incomplete, and both the intercalation process and thermal stability of the included organic moieties are far from being completely understood. In this study, we present a thorough solid-state NMR characterization of HLaNb2O7·xH2O intercalated with different amounts of octylamine, or with decylamine. Samples were analyzed as prepared, and after th…
Persistent photovoltage in methylammonium lead iodide perovskite solar cells
2014
Open circuit voltage decay measurements are performed on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier recombination dynamics. The measurements are compared to the two reference polymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and PTB7:PC70BM blends. In the perovskite devices, two very different time domains of the voltage decay are found, with a first drop on a short time scale that is similar to the organic solar cells. However, two major differences are also observed. 65-70% of the maximum photovoltage persists on much longer timescales, and the recombination dynamics are dependent on the illumination intensity.
Mixed Iodide-Bromide Methylammonium Lead Perovskite-based Diodes for Light Emission and Photovoltaics.
2015
Vacuum deposition techniques are used to prepare mixed iodide–bromide methylammonium lead perovskite diodes via an intermediate double layer of the pure iodide and bromide perovskites. The diodes lead to bright electroluminescence, whose emission spectra maxima shift from the infrared toward the visible with increasing bromide content. When illuminated with AM1.5 simulated sunlight the devices function as efficient solar cells with power conversion efficiencies as high as 12.9%.