Electronic structures and elastic properties of a family of metal-free perovskites

Li, Kai; Dong, Liyuan; Xu, Haoxiang; Qin, Yan; Li, Zhigang; Azeem, Muhammad; Li, Wei; Bu, Xian‐He

doi:10.1039/c9qm00133f

Cited by 48 publications

(57 citation statements)

References 39 publications

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“…The absorption coefficient was unusually small, <30 cm −1 , at saturation absorption at short wavelengths. From the elemental assignment of the partial density of states (PDOS) for DABCONH 4 Br 3 ( Figure 6B), we noted that the valence band maximum (VBM) was predominantly Br p-states while the conduction band minimum (with an overall weak DOS, which might help to explain the low absorption coefficient) was predominantly C (from DABCO) and N (which could come from either/both DABCO or/and ammonium), as well as some H. The other studies that showed elemental PDOS breakdown in their DOS [16,28,29] can be interpreted to agree with this, except for ref. [28], where the A cation was piperazine, and the conduction band minimum (CBM) appeared to be composed of halide s orbitals.…”

Section: Optoelectronic and Charge-transport Propertiesmentioning

confidence: 87%

“…[18] Refs. [16,18,[27][28][29] all calculated band structures for a variety of ANH 4 X 3 compounds and for a variety of reasons (including to predict/understand ferroelectric, mechanical, and nonlinear optical (NLO) properties). Ref.…”

Section: Optoelectronic and Charge-transport Propertiesmentioning

confidence: 99%

“…There have been three reports on mechanical properties of metal-free perovskites for MDABCONH 4 I 3 (experimental), [17] MDABCONH 4 X 3 (X = Cl, Br, and I) (calculated), [27] and piperazine ammonium halide hydrate denoted as PIPX (X = Cl, Br, and I) (calculated and also experimental for PIPBr). [28] Ref. [28] gives a table (table S5) comparing elastic constants, including shear, bulk, and Young's moduli, of PIPX with those of other compounds, including MDABCONH 4 X 3 from ref.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…[28] Ref. [28] gives a table (table S5) comparing elastic constants, including shear, bulk, and Young's moduli, of PIPX with those of other compounds, including MDABCONH 4 X 3 from ref. [27].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

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Metal‐Free Organic Halide Perovskite: A New Class for Next Optoelectronic Generation Devices

Song

Hodes

Zhao

et al. 2021

Advanced Energy Materials

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Pb and Sn; X = halogen) was shown to be feasible as sensitizers for photovoltaic cells, [2] and 2012, when conversion efficiencies around 10% were first demonstrated for solid-state cells, [3,4] that the field exploded. Since then, the power conversion efficiency (PCE) of perovskite solar cells has increased to 25.5%, surpassing Cu(In,Ga)Se 2 (CIGS) and cadmium telluride (CdTe), and approaching that of single crystal silicon solar cells. [5] The structural formula of halide perovskite materials is generally ABX 3 , where A and B are two different cations and X is a halide anion (Cl − , Br − , or I −). [6] Currently metal-based organic (usually) halide perovskites have taken a dominant position for optoelectronics due to confluence of several factors, including extremely high optical absorption, long charge lifetimes/diffusion lengths, dominant point defects that only generate shallow levels, and grain boundaries that are essentially benign. [4,7,8] However, these metal-based perovskites do have some intrinsic problems. 1) The toxic solvents involved in fabrication including N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO-not particularly toxic by itself but can transport potentially toxic dissolved species rapidly through the skin), gamma-butyrolactone (GBL), and chlorobenzene. 2) Metal-based perovskites may become available to humans through leaching and transport through water, air, and soil. Toxins like Pb accumulate in the human body and can cause several brain-related symptoms such as memory problems and intellectual disability. [9,10] These toxic materials are not compatible with wearable devices. 3) In general, Pb-based perovskites are prone to attack by moisture, which causes material (and device) degradation. [11,12] Bi-based perovskites are more stable but have relatively poor chargetransport properties. [13] Only recently, metal-free halide organic perovskites, a novel member of the perovskite family, have emerged. [14] Metal-free perovskites take advantage not only of the ABX 3 perovskite structure, but also of the tunability, diversity, and lightweight nature of organic materials. Meanwhile, these materials can be fabricated from aqueous solution and are fully degradable, which hold promise for eco-friendly fabrication and application. Despite the initial discovery of metalfree perovskites in 2002 by Bremner et al., [14] and a similar paper on perchlorate perovskites in 2011, [15] advancements have been reported only during the past 2 years, including Even though the metal-halide perovskites are attracting ever-increasing interest for their breakthrough efficiencies in photovoltaics, light-emitting diodes (LED), X-ray imaging, and general optoelectronics, it was not until very recently that metal-free halide perovskites become recognized, not only for their good optoelectronic performance, but also for their wide chemical diversity, tunability, lightweight, mechanical flexibility, and ecofriendly processability. The community is turning their attention to these lightweight semiconductors, and p...

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Section: Optoelectronic and Charge-transport Propertiesmentioning

confidence: 87%

Section: Optoelectronic and Charge-transport Propertiesmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

See 2 more Smart Citations

Metal‐Free Organic Halide Perovskite: A New Class for Next Optoelectronic Generation Devices

Song

Hodes

Zhao

et al. 2021

Advanced Energy Materials

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“…[8] These materials are nontoxic, mechanically flexible, and lightweight compared to traditional metal-based halide perovskites. The functionality of these materials has recently been explored as metal-free ferroelectrics, [4,9] mechanical/elastic properties, [10][11][12] and their non-linear optical properties have been reported in a theoretical study. [13] Unfortunately, 17 years after the initial discovery of metal-free halide perovskites, there have been no reports about their charge transport characteristics and only one report (see Supporting Information of ref.…”

mentioning

confidence: 99%

Metal‐Free Halide Perovskite Single Crystals with Very Long Charge Lifetimes for Efficient X‐ray Imaging

et al. 2020

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X-ray detectors are extensively utilized, including in medical diagnosis, scientific research, and security screening. So far, X-ray detectors have been developed mainly on the basis of metal-based semiconductors. Recently, in addition to traditional Si, Cd(Zn)Te and Ge, crystals based on metal halide perovskites have emerged as a new generation of semiconductors for radiation detection due to their high-Z elements Pb, Bi, and Br. [1-3] However, the requirements for practical wearable materials to be lightweight, economically inexpensive, and environmentally friendly motivate the exploration for nontoxic, low-cost, and simple organic compounds. [4] Lightweight semiconductors based on conjugated molecules or polymers have been demonstrated in a proof-of-principle manner for direct X-ray detection, including 4-hydroxycyanobenzene (4HCB), 1,8-naphthaleneimide (NTI), 1,5-dinitronaphthalene, and rubrene. [5-7] However, the fabrication of large-scale crystals with exceptionally Metal-free halide perovskites, as a specific category of the perovskite family, have recently emerged as novel semiconductors for organic ferroelectrics and promise the wide chemical diversity of the ABX 3 perovskite structure with mechanical flexibility, light weight, and eco-friendly processing. However, after the initial discovery 17 years ago, there has been no experimental information about their charge transport properties and only one brief mention of their optoelectronic properties. Here, growth of large single crystals of metalfree halide perovskite DABCO-NH 4 Br 3 (DABCO = N-N′-diazabicyclo[2.2.2] octonium) is reported together with characterization of their instrinsic optical and electronic properties and demonstration, of metal-free halide perovskite optoelectronics. The results reveal that the crystals have an unusually large semigap of ≈16 eV and a specific band nature with the valence band maximum and the conduction band minimum mainly dominated by the halide and DABCO 2+ , respectively. The unusually large semigap rationalizes extremely long lifetimes approaching the millisecond regime, leading to very high charge diffusion lengths (tens of µm). The crystals also exhibit high X-ray attenuation as well as being lightweight. All these properties translate to high-performance X-ray imaging with sensitivity up to 173 µC Gy air −1 cm −2. This makes metal-free perovskites novel candidates for the next generation of optoelectronics.

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Giant Emission Enhancement from Hybrid Manganese Bromide Via Pressure‐Induced Band‐Edge Carrier Reconfiguration

Li,

Gao

et al. 2024

Adv Funct Materials

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Pressure‐induced emission enhancement (PIEE) is a novel phenomenon in contrast to conventional pressure‐induced emission quenching, and has attracted considerable attention owing to the potential application of materials with this effect as optical pressure‐sensing devices. The urgent need and significant significance lie in the design and exploration of systems that possess high‐efficiency PIEE. Here, a large PIEE in a novel zero‐dimensional (0D) hybrid manganese bromide is realized, (BPPH)2MnBr4·1.5CH3CN [BPPH+ = bis(triphenylphosphine)iminium]. The experimental and theoretical results demonstrate that such emission enhancement is primarily attributed to the pressure‐induced reconfiguration of electronic band alignment and resultant redistribution of band‐edge excitons. Under compression, the electronic bandgap of (MnBr4)2− experiences a more rapid reduction compared to that of the organic cations. Consequently, this leads to the gradual closure of the charge transfer pathway from (MnBr4)2− to BPPH+. This progression results in a higher retention of excitons on (MnBr4)2−, amplifying the efficiency of Mn2+ d–d transitions, and leading to a substantial enhancement in emission. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of PIEE systems.

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Electronic structures and elastic properties of a family of metal-free perovskites

Abstract: The fundamental electronic structures and elastic properties of a family of metal-free perovskites were systematically investigated using a combined theoretical-experimental approach.

Cited by 48 publications

References 39 publications

Metal‐Free Organic Halide Perovskite: A New Class for Next Optoelectronic Generation Devices

Metal‐Free Organic Halide Perovskite: A New Class for Next Optoelectronic Generation Devices

Metal‐Free Halide Perovskite Single Crystals with Very Long Charge Lifetimes for Efficient X‐ray Imaging

Giant Emission Enhancement from Hybrid Manganese Bromide Via Pressure‐Induced Band‐Edge Carrier Reconfiguration

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