Mixed-Halide Perovskite Film-Based Neuromorphic Phototransistors for Mimicking Experience-History-Dependent Sensory Adaptation

A thiourea additive-based quadruple cation lead halide perovskite with an ultra-large grain size for efficient perovskite solar cells

Nanoscale ◽

10.1039/c9nr07377a ◽

2019 ◽

Vol 11 (45) ◽

pp. 21824-21833 ◽

Cited By ~ 9

Author(s):

Jyoti V. Patil ◽

Sawanta S. Mali ◽

Chang Kook Hong

Keyword(s):

Thin Films ◽

Grain Size ◽

Solar Cells ◽

Power Conversion Efficiency ◽

Conversion Efficiency ◽

Power Conversion ◽

Perovskite Solar Cells ◽

Inorganic Perovskite ◽

Halide Perovskite ◽

Lead Halide

Controlling the grain size of the organic–inorganic perovskite thin films using thiourea additives now crossing 2 μm size with >20% power conversion efficiency.

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Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

10.26434/chemrxiv.7629467.v3 ◽

2019 ◽

Author(s):

Young-Kwang Jung ◽

Joaquin Calbo ◽

Ji-Sang Park ◽

Lucy D. Wahlley ◽

Sunghyun Kim ◽

...

Keyword(s):

First Principles ◽

Room Temperature ◽

Stokes Shift ◽

Green Luminescence ◽

Counter Ions ◽

Self Consistent ◽

Deep Ultraviolet ◽

Halide Perovskite ◽

Related Compounds ◽

Level Analysis

Cs4PbBr6 is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr64- octahedra with Cs+ counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs4PbBr6. We find a heavily compensated system where the room-temperature carrier concentrations (< 109 cm-3) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br3) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission.

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Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

10.26434/chemrxiv.7629467 ◽

2019 ◽

Cited By ~ 1

Author(s):

Young-Kwang Jung ◽

Joaquin Calbo ◽

Ji-Sang Park ◽

Lucy D. Wahlley ◽

Sunghyun Kim ◽

...

Keyword(s):

First Principles ◽

Room Temperature ◽

Stokes Shift ◽

Green Luminescence ◽

Counter Ions ◽

Self Consistent ◽

Deep Ultraviolet ◽

Halide Perovskite ◽

Related Compounds ◽

Level Analysis

Cs4PbBr6 is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr64- octahedra with Cs+ counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs4PbBr6. We find a heavily compensated system where the room-temperature carrier concentrations (< 109 cm-3) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br3) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission.

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Hollow Metal Halide Perovskite Nanocrystals with Efficient Blue Emissions

10.26434/chemrxiv.9636824.v1 ◽

2019 ◽

Author(s):

Michael Worku ◽

Yu Tian ◽

Chenkun Zhou ◽

Haoran Lin ◽

Maya Chaaban ◽

...

Keyword(s):

Precursor Solution ◽

Visible Spectral Region ◽

Metal Halide ◽

Synthetic Control ◽

Perovskite Nanocrystals ◽

Highly Efficient ◽

Quantum Confinement Effects ◽

Metal Halide Perovskite ◽

Lead Bromide ◽

Halide Perovskite

Metal halide perovskite nanocrystals (NCs) have emerged as a new generation light emitting materials with narrow emissions and high photoluminescence quantum efficiencies (PLQEs). Various types of perovskite NCs, e.g. platelets, wires, and cubes, have been discovered to exhibit tunable emissions across the whole visible spectral region. Despite remarkable advances in the field of metal halide perovskite NCs over the last few years, many nanostructures in inorganic NCs have yet been realized in metal halide perovskites and producing highly efficient blue emitting perovskite NCs remains challenging and of great interest. Here we report for the first time the discovery of highly efficient blue emitting cesium lead bromide perovskite (CsPbBr3) NCs with hollow structures. By facile solution processing of cesium lead bromide perovskite precursor solution containing additional ethylenediammonium bromide and sodium bromide, in-situ formation of hollow CsPbBr3 NCs with controlled particle and pore sizes is realized. Synthetic control of hollow nanostructures with quantum confinement effects results in color tuning of CsPbBr3 NCs from green to blue with high PLQEs of up to 81 %. <div> </div>

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