Transformation of Sintered CsPbBr3 Nanocrystals to Cubic CsPbI3 and Gradient CsPbBrxI3–x through Halide Exchange

Hoffman, Jacob B.; Schleper, A. Lennart; Kamat, Prashant V.

doi:10.1021/jacs.6b04661

Cited by 343 publications

(393 citation statements)

References 58 publications

(109 reference statements)

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“…Fourier transformed velocity auto-correlation function (VAC) from ab initio molecular dynamics (MD) simualtions at 600 K above the critical temperature T C ( 583 K) [35] for the cubic phase ( Figure S1a, Supporting Information) shows that the overall MD spectra agree with 0 K lattice phonon density of states (DOS), and both LO1 and LO2 energy DOS do not change much ( Figure S1b, Supporting Information). Therefore, we assume that at high temperatures, phonon spectra of high energy LO modes are not severely affected.…”

Section: Various Types Of Configurations Of A-site Cations With Surromentioning

confidence: 99%

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

Myung

Yun

Lee

et al. 2018

Advanced Energy Materials

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As the race towards higher efficiency for inorganic/organic hybrid perovskite solar cells (PSCs) is becoming highly competitive, a design scheme to maximize carrier transport towards higher power efficiency has been urgently demanded. Here, we unravel a hidden role of A-site cation of PSCs in carrier transport which has been largely neglected, i.e., tuning the Frhlich electron-phonon (e-ph) coupling of longitudinal optical (LO) phonon by A-site cations. The key for steering Frhlich polaron is to control the interaction strength and the number of proton (or lithium) coordination to halide ion. The coordination to I − alleviates electron-phonon scattering by either decreasing the Born effective charge or absorbing the LO motion of I. This novel principle discloses lower electron-phonon coupling by several promising organic cations including hydroxyl-ammonium cation (NH3OH + ) and possibly Li + solvating methylamine (Li + ···NH2CH3) than methyl-ammonium cation. A new perspective on the role of A-site cation could help in improving power efficiency and accelerating the application of PSCs.Solar energy is a highly efficient and eco-friendly source for future energy harvesting. In particular, inorganic/organic PSCs of ABX3 (A = Cs+, CH3NH3+, etc.; B = Pb2+; X = Cl-, Br-or I-) show extraordinary solar cell efficiencies exceeding 22 % [1] with unusual characteristics, [2][3][4] which attracts tremendous attention as most promising large-scale solar energy conversion materials.[5] One key origin of high efficiency arises from high carrier mobility (µ) 10 -8] even in the presence of defects.[9] While the carrier transport exhibits remarkable features in experiments, there is still a gap of understanding. One aspect of this difficulty stems from significant electron-phonon (e-ph) interactions, [2,8,[10][11][12][13] which complicates band pictures. Another aspect is due to the A-site cation that rotates [14] or even diffuses across the material, causing I-V hysteresis.[15] Although recent discovery of various types of cations has greatly advanced the efficiency of PSCs, [16] it also has brought about more ambiguity on the role of cations.In general, electrons in polar crystal experience the deformation potential in addition to Bloch potential due to large polarity of ionic bonding. The charge carriers are then described by polaron quasiparticles originating from coupling between electrons and phonons. For PSCs, there has been a critical debate on the source of e-ph coupling, acoustic vs. longitudinal. From the temperature dependence of µ ∼ T −3/2 around room temperature, acoustic phonons have been considered as the main source of e-ph coupling. [11,17] In this study, we unveil a hidden role of A-site cation in polaron picture of PSCs by accounting for the e-ph interactions regarding both A-site cation and LO phonon scattering at the first principles level. [18,19] We used the Frohlich polaron model [23] which is suitable for large bandwidth (W ) limit W ω ph by considering Frohlich vertex. [24] We cast light on the role o...

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Section: Various Types Of Configurations Of A-site Cations With Surromentioning

confidence: 99%

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

Myung

Yun

Lee

et al. 2018

Advanced Energy Materials

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“…In the first step, the effect of the PbBr 2 ·DMF adduct is considered to be important for the formation of CsPb 2 Br 5 . Without the existence of the adduct, the reaction process should be different [19,26]. FT-IR was conducted to confirm the existence of the adduct.…”

Section: Characterizationmentioning

confidence: 99%

Sequential deposition method fabricating carbonbased fully-inorganic perovskite solar cells

Ding

Ren

et al. 2017

Sci. China Mater.

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Hybrid organic-inorganic halide perovskite material has been considered as a potential candidate for various optoelectronic applications. However, their high sensitivity to the environment hampers the actual application. Hence the technology replacing the organic part of the hybrid solar cells needs to be developed. Herein, we fabricated fullyinorganic carbon-based perovskite CsPbBr 3 solar cells via a sequential deposition method with a power conversion efficiency of 2.53% and long-time stability over 20 d under ambient air conditions without any encapsulation. An evolution process from tetragonal CsPb 2 Br 5 to CsPb 2 Br 5 -CsPbBr 3 composites to quasi-cubic CsPbBr 3 was found, which was investigated by scanning electron microscopy, X-ray diffraction spectra, UV-vis absorption spectra and Fourier transform infrared spectroscopy. Detailed evolution process was studied to learn more information about the formation process before 10 min. Our results are helpful to the development of inorganic perovskite solar cells and the CsPb 2 Br 5 based optoelectronic devices.

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“…Hoffman et al 56 used a CsPbBr 3 QDs film and transformed it to a cubic CsPbI 3 phase by dipping the CsPbBr 3 QDs layer (∼75-nm thickness) into the iodide precursor dissolved in OLA/OLAM/1-ODE at 75°C. Hence, the method of halide exchange process in CsLHQDs is very simple and this process can be avoided using the surface functionalization with thiol-based polyhedral oligomeric molecules when not required.…”

Section: Halide Exchange In Cs-lhqdsmentioning

confidence: 99%

“…Mixed solvents such as ethyl acetate and acetone (5∶1 v/v), 90% hexane, and 10% heptane were also used for this purpose. 54,56 The obtained QDs are washed with solvents upon centrifugation and produced in powder form which is used for further structural and morphological analysis. Multiple washing of Cs-LHQDs results in some adverse phenomena such as the self-soldering effect (formation of microcrystal of QDs) observed in low temperature synthesized Cs-LHQDs.…”

Section: Introductionmentioning

confidence: 99%

Cesium lead halide ( CsPbX ₃, X = Cl , Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status

2016

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, "Cesium lead halide (CsPbX 3 , X ¼ Cl, Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status," J. Photon. Energy 6(4), 042001 (2016), doi: 10.1117/1.JPE.6.042001. Abstract. Metal halide-based perovskite quantum dots (QDs) have emerged as promising materials for optoelectronics and future energy applications. Among them, cesium lead halide-based perovskite quantum dots (Cs-LHQDs) have been found to be potential luminescent candidates and alternatives for the II-VI and I − III − VI 2 groups semiconductor nanoparticles. These perovskites provide an excellent quantum yield (90%) larger than any other semiconductor QDs. At present, synthesis of Cs-LHQDs has been successfully achieved through a traditional colloidal-based hot-injection method and a room temperature precipitation method. Some of the interesting results in their structural, optical, and morphological properties are being analyzed to understand their energy-transfer mechanism in the colloidal state. Morphology of nanoplates, nanowires, nanocube, and nanosheets in these materials confirms their physical parametersdependent self-assembly nature in a colloidal medium. Their potential use for light emitting diodes, photodetectors, and lasers is also highly motivated. This review provides a collective view of recent developments made in the synthesis of Cs-LHQDs and their properties. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Transformation of Sintered CsPbBr₃ Nanocrystals to Cubic CsPbI₃ and Gradient CsPbBr_xI_3–x through Halide Exchange

Cited by 343 publications

References 58 publications

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

Sequential deposition method fabricating carbonbased fully-inorganic perovskite solar cells

Cesium lead halide ( CsPbX ₃, X = Cl , Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status

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Transformation of Sintered CsPbBr3 Nanocrystals to Cubic CsPbI3 and Gradient CsPbBrxI3–x through Halide Exchange

Cited by 343 publications

References 58 publications

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

Sequential deposition method fabricating carbonbased fully-inorganic perovskite solar cells

Cesium lead halide ( CsPbX 3, X = Cl , Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status

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Transformation of Sintered CsPbBr₃ Nanocrystals to Cubic CsPbI₃ and Gradient CsPbBr_xI_3–x through Halide Exchange

Cesium lead halide ( CsPbX ₃, X = Cl , Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status