66 research outputs found
Permanent Lattice Compression of Lead-Halide Perovskite for Persistently Enhanced Optoelectronic Properties
Under mild mechanical pressure, halide perovskites show enhanced optoelectronic properties. However, these improvements are reversible upon decompression, and permanent enhancements have yet to be ..
Contributions of the lead-bromine weighted bulk bands to the occupied density of states of the hybrid tri-bromide perovskites
Multi-cation perovskites prevent carrier reflection from grain surfaces
© 2020, The Author(s), under exclusive licence to Springer Nature Limited. The composition of perovskite has been optimized combinatorially such that it often contains six components (AxByC1âxâyPbXzY3âz) in state-of-art perovskite solar cells. Questions remain regarding the precise role of each component, and the lack of a mechanistic explanation limits the practical exploration of the large and growing chemical space. Here, aided by transient photoluminescence microscopy, we find that, in perovskite single crystals, carrier diffusivity is in fact independent of composition. In polycrystalline thin films, the different compositions play a crucial role in carrier diffusion. We report that methylammonium (MA)-based films show a high carrier diffusivity of 0.047 cm2 sâ1, while MA-free mixed caesium-formamidinium (CsFA) films exhibit an order of magnitude lower diffusivity. Elemental composition studies show that CsFA grains display a graded composition. This curtails electron diffusion in these films, as seen in both vertical carrier transport and surface potential studies. Incorporation of MA leads to a uniform grain core-to-edge composition, giving rise to a diffusivity of 0.034 cm2 sâ1 in CsMAFA films. A model that invokes competing crystallization processes allows us to account for this finding, and suggests further strategies to achieve homogeneous crystallization for the benefit of perovskite optoelectronics
Solution-processed semiconductors for next-generation photodetectors
Efficient light detection is central to modern science and technology.Current photodetectors mainly use photodiodes based on crystalline inorganic elementalsemiconductors, such as silicon, or compounds such as IIIâV semiconductors. Photodetectorsmade of solution-processed semiconductors â which include organic materials, metal-halideperovskites and quantum dots â have recently emerged as candidates for next-generation lightsensing. They combine ease of processing, tailorable optoelectronic properties, facile integrationwith complementary metalâoxideâsemiconductors, compatibility with flexible substrates andgood performance. Here, we review the recent advances and the open challenges in the field ofsolution-processed photodetectors, examining the topic from both the materials and the deviceperspective and highlighting the potential of the synergistic combination of materials and deviceengineering. We explore hybrid phototransistorsand their potential to overcome trade-offsin noise, gain and speed, as well as the rapid advances in metal-halide perovskite photodiodesand their recent application in narrowband filterless photodetection
Efficient Blue Perovskite LightâEmitting Diodes Boosted by 2D/3D Energy Cascade Channels
High-Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed-Laser Irradiation in Liquid
Nanoparticles of hybrid organic-inorganic perovskites have attracted a great deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry, compared with microcrystalline, thin-film, or bulk metal halides. Here we present a novel one-step synthesis of organolead bromide perovskite nanocrystals based on pulsed-laser irradiation in a liquid environment (PLIL). Starting from a bulk CH3NH3PbBr3 crystal, our PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature. The resulting nanoparticles are characterized by high crystallinity and are completely free of any microscopic product or organic coating layer. We also demonstrate the straightforward inclusion of laser-generated perovskite nanocrystals in a polymeric matrix to form a nanocomposite with single- and two-photon luminescence properties
Insight into the Origins of Figures of Merit and Design Strategies for Organic/Inorganic LeadâHalide Perovskite Solar Cells
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