Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides

Maughan, Annalise E.; Ganose, Alex M.; Almaker, Mohammed A.; Scanlon, David O.; Neilson, James R.

doi:10.1021/acs.chemmater.8b01549

Cited by 121 publications

(141 citation statements)

References 68 publications

(127 reference statements)

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“…Their crystal structure is depicted by Maughan et al, as shown in Figure 9a,b. Although there are some conflicting reports [88,112,124,169] on the room temperature carrier mobility of Cs 2 SnI 6 , the origin of conductivity in this compound has been hypothesized to stem from (a) the possession of dispersive conduction band states and (b) the presence of iodine vacancies. Cs 2 SnI 6 compound exhibits intrinsic n-type electrical conductivity and other fascinating features such as direct bandgap, air and moisture stability, and strong visible light absorption.…”

Section: Vacancy Ordered Halide Double Perovskitesmentioning

confidence: 99%

“…[169] The polaron characteristics and charge transport behavior in vacancy-ordered double perovskites can be tuned by introducing cooperative octahedral tilting distortions. [169] The polaron characteristics and charge transport behavior in vacancy-ordered double perovskites can be tuned by introducing cooperative octahedral tilting distortions.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

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Progress of Lead‐Free Halide Double Perovskites

Igbari

Wang

Liao

2019

Advanced Energy Materials

380

305

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Although impressive performance has been obtained, PSCs are still far from commercial or real-life availability due to serious issues such as toxicity [15,16] and poor stability to heat, [17] oxygen, [18] moisture, [19,20] electric field, [21] and light. [18,22] The toxic nature of hybrid organic-inorganic lead halide perovskites has been traced to the presence of Pb in its chemical composition. [15,16,[23][24][25] Pb 2+ readily dissolves in water (e.g., rain water) to form a toxic solution capable of causing serious environmental pollution, harmful to human beings and the ecosystem. Besides their sensitivity to moisture, oxygen, light, electric field, or thermal stress, an existing self-degradation pathway [26,27] is also a big issue in hybrid organic-inorganic lead halide perovskites. Mixed-halide and mixed-cation perovskites have been investigated to address these issues. [28][29][30][31][32] The group IV elements, tin (Sn) [23,[33][34][35] and germanium (Ge), [34,36] have been employed as the replacements for Pb. However, the device performance through this approach has fallen short of the Pb-based ones. For example, the PCEs reported for Sn-based perovskite solar cells are usually less than 10%. [23,[33][34][35][37][38][39][40] In addition, the easy oxidation of Sn and Ge from the +2 state to the +4 state due to their high energy 5s and 4s orbitals makes them less promising for application in stable and long-term PSCs. [41] High throughput calculations also demonstrate that these substitutions are likely to compromise the ideal optoelectronic properties of MAPbI 3 . [42,43] Furthermore, low dimensional (e.g., 2D, 1D, and 0D) perovskites have also been used to address the stability issues in PSCs. [44][45][46][47][48] Recently, a stabilized PCE of 21.7% resulting from a 2D/3D bilayer PSC was reported. [49] However, the highest certified PCE in a 2D-only planar PSC is 15.3%, [50] which is far below that of their 3D perovskite-based counterparts. It thus stimulates the interest to develop new classes of materials which can solve the issues of toxicity and stability while still maintaining the fascinating properties of lead-based perovskite materials.Recent theoretical calculations demonstrate that a halide double perovskite structure, A 2 B′B″X 6 , which could be formed through a replacement of two toxic Pb 2+ in the crystal lattice with a pair of nontoxic heterovalent (i.e., monovalent and trivalent) metal cations, is a promising alternative to realize high-performance, lead-free, and stable PSCs. [51,52] Although, spectroscopic limited maximum efficiency (SLME) calculations revealed an efficiency limit less than 8% for the most prominent member www.advancedsciencenews.com double perovskites with a vacancy ordered structure. [88] In particular, the unit cell axis of Cs 2 AgBiBr 6 is given to be ≈11.25 Å, [25] which is two times larger than that of MAPbBr 3 (≈5.92 Å). [89] Both Ag + and Bi 3+ occupy the B-site of the crystal lattice with slightly varied metal-halide bond lengths. The dissimilar bond lengths st...

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Section: Vacancy Ordered Halide Double Perovskitesmentioning

confidence: 99%

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Progress of Lead‐Free Halide Double Perovskites

Igbari

Wang

Liao

2019

Advanced Energy Materials

380

305

View full text Add to dashboard Cite

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“…We used these metrics to estimate the limit to Rb + doping of CsPbBr 3 ( t = 0.92) with Rb + to increase the bandgap. Finite Rb + incorporation results in further tilting of the PbX 6 octahedra, reducing the overall orbital overlap and hence opening up the bandgap of CsPbBr 3 while simultaneously reducing the tolerance factor . However, it has been reported that an upper bound of 70% Rb + exists in a mixed cation perovskite QD, as pure RbPbBr 3 does not exist under ambient conditions …”

Section: Peled Electroluminescence Performance Metricsmentioning

confidence: 99%

Spectrally Tunable and Stable Electroluminescence Enabled by Rubidium Doping of CsPbBr₃ Nanocrystals

Todorovič

Chen

et al. 2019

Advanced Optical Materials

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quantum yields (PLQYs), as well as their tunability through size and composition which enables emission wavelengths that span the full visible spectrum. [1,[10][11][12] In contrast with conventional epitaxially grown semiconductors, solution-processed quantum dots are synthesized at lower temperatures, which enables low-cost device fabrication and compatibility with flexible plastic substrates. In the hot-injection synthesis, metal salt precursors of the form AX and BX 2 are solubilized in a solvent that contains stabilizing ligands, after which the A-site organometallic solution is injected at an elevated temperature into the solution containing BX 2 , and colloidal QDs emerge within seconds. [1,11,13] Perovskite LEDs (PeLEDs) have recently achieved high external quantum efficiencies (EQEs) above 20% in the red and green; but blue PeLEDs have lagged behind their red and green counterparts. [14,15] Low EQEs in blue devices have been attributed to increased degradation pathways through increased defect formation at higher driving voltages; as well as due to lower PLQYs of the initial active layer. [16][17][18] Additionally, PeLED research on deep-blue emission (<470 nm) has been limited. The Rec.2020 standard set by the International Telecommunications Union Radiocommunication (ITU-R) requires blue emitters having emission centered at 467 nm and, by achieving a narrow full-width at halfmaximum (FWHM <25 nm) and minimal red tail, to meet the color coordinate: [(x blue = 0.131, y blue = 0.046)]. [19] In order to achieve blue emission in perovskites, halide mixing and quantum confinement strategies are employed. Blue perovskite QDs have relied on anion mixtures containing both Br − and Cl − within the APbX 3 cubic/orthorhombic nanocrystal, such as in the archetypal CsPbBr 3−x Cl x to obtain the desired emission. [1,11,20] These mixed halide systems have enabled high PLQYs and impressively narrow FWHM of 12 nm in solution for pure CsPbCl 3 , and roughly 25 nm for mixed Br/Cl systems. [10] Utilizing this strategy, Song et al. achieved an EQE of 0.07% at an emission wavelength of 455 nm and a peak brightness of 742 cd m −2 . [20] A record high EQE of 1.9% was reported by Pan et al. at 490 nm, but these devices displayed low luminance. [21] Unfortunately, mixed halide PeLEDs suffer from color instability under operating conditions: phase segregation into pure Cl − and Br − phases occurs under voltage bias. [22] This leads to a red-shift of the electroluminescence (EL) spectra. [22] Perovskite nanocrystals exhibit high photoluminescence quantum yields (PLQYs) and tunable bandgaps from ultraviolet to infrared. However, blue perovskite light-emitting diodes (LEDs) suffer from color instability under applied bias. Developing narrow-bandwidth deep-blue emitters will maximize the color gamut of display technologies. Mixed anion approaches suffer from halide segregation that leads to their spectral instability. Here instead, a mixed cation strategy is employed whereby Rb + is directly incorporated during synthesis into CsPbBr 3...

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“…Substitution of Cs + ion with relatively smaller Rb + ion in the vacancy‐ordered double perovskite Cs 2 SnI 6 has been investigated, with significant changes in structure and electronic behavior observed . The conductivity measurement of Rb 2 SnI 6 indicates that it is a natural n‐type semiconductor, but the carrier mobility is reduced by about 50 times compared with Cs 2 SnI 6 .…”

Section: Materials and Structuresmentioning

confidence: 99%

Structurally Stabilizing and Environment Friendly Triggers: Double‐Metallic Lead‐Free Perovskites

et al. 2019

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Lead halide perovskite (ABX3) has attracted considerable attention due to its applicability as absorber layers in highly efficient photovoltaic cells. With regard to the lead toxicity, double‐metallic lead‐free perovskite, A2BIBIIIX6, in which the neighboring B+ and B3+ sites in the crystal microstructure are alternately occupied by monovalent‐metal and trivalent‐metal cations, is regarded to be a promising alternative to the widely used lead‐based perovskites. This review aims to summarize the recent advances in the new class of A2BIBIIIX6 double‐metallic lead‐free perovskites. In particular, the electronic structure, synthesis, property, and their applications in devices, for example, photovoltaics, photodetectors, and light emitting diodes, is carefully classified and presented. Notably, the theoretical calculations point out that there is much room toward potential applications for this new class of perovskite materials. The present review provides a holonomic conclusion and opens new perspectives toward realizing higher performance of A2BIBIIIX6‐based devices.

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Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides

Cited by 121 publications

References 68 publications

Progress of Lead‐Free Halide Double Perovskites

Progress of Lead‐Free Halide Double Perovskites

Spectrally Tunable and Stable Electroluminescence Enabled by Rubidium Doping of CsPbBr₃ Nanocrystals

Structurally Stabilizing and Environment Friendly Triggers: Double‐Metallic Lead‐Free Perovskites

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Tolerance Factor and Cooperative Tilting Effects in Vacancy-Ordered Double Perovskite Halides

Cited by 121 publications

References 68 publications

Progress of Lead‐Free Halide Double Perovskites

Progress of Lead‐Free Halide Double Perovskites

Spectrally Tunable and Stable Electroluminescence Enabled by Rubidium Doping of CsPbBr3 Nanocrystals

Structurally Stabilizing and Environment Friendly Triggers: Double‐Metallic Lead‐Free Perovskites

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Spectrally Tunable and Stable Electroluminescence Enabled by Rubidium Doping of CsPbBr₃ Nanocrystals