Organic–inorganic hybrids, which synergize the merits of organic and inorganic materials, have emerged as a new class of highly versatile functional materials with tailored properties and enhanced ...energy conversion efficiency. In this Focus Review, state-of-the-art results on organic–inorganic hybrids, used for water splitting and generation of hydrogen as a clean and renewable fuel, are concisely summarized. Two classes of hybrid materials, i.e., organic–inorganic nanocomposites and hybrid halide perovskites, are reviewed and compared for designing photoelectrochemical cells. Furthermore, promising design strategies to enhance the device performance and stability are discussed.
Metal halides with low‐dimensional molecular structures are the rising stars in the horizon of functional materials research. Among them, 1D metal halide hybrids are very promising for future ...optoelectronic applications because of their unusual photophysical properties resulting from strong quantum confinement. In the past few years, besides lead‐based 1D metal halide hybrids, research has been extended to lead‐free organic and all‐inorganic metal halides. Due to near‐unity photoluminescence quantum yield and excellent structural stability, all‐inorganic 1D metal halides are suitable for environmentally friendly optoelectronic devices. Moreover, the distortion and connectivity mode of metal halide octahedra arouse the formation of self‐trapped excitons within 1D metal halides, thus endowing the materials with distinct optical properties. Recent investigations have revealed many exciting characteristics of this new class of materials, such as ferroelectricity, ferromagnetism, optical cooling, and so on. This perspective presents not only structure–property correlations and recent applications of 1D metal halides but also the existing challenges and future research directions.
Molecular 1D‐networked metal halides are large crystals formed with metal halide quantum wires that are separated by cationic lattices in bulk matrixes. Herein, the latest breakthroughs in understanding the fundamental properties of 1D metal halide materials as applied to various optoelectronic applications are reviewed. Finally, the existing challenges and outline for future research directions are offered.
Abstract The rapid development of mixed‐halide perovskites has established a versatile optoelectronic platform owing to their extraordinary physical properties, but there remain challenges toward ...achieving highly reliable synthesis and performance, in addition, post‐synthesis approaches for tuning their photoluminescence properties after device fabrication remain limited. In this work, an effective approach is reported to leveraging hot electrons generated from plasmonic nanostructures to regulate the optical properties of perovskites. A plasmonic metasurface composed of Au nanoparticles can effectively tailor both photoluminescence and location‐specific phase segregation of mixed‐halide CsPbI 2 Br thin films. The ultrafast transient absorption spectroscopy measurements reveal hot electron injection on the timescale of hundreds of femtoseconds. Photocurrent measurements confirm the hot‐electron‐enhanced photon‐carrier conversion, and in addition, gate‐voltage tuning of phase segregation is observed because of correlated carrier injection and halide migration in the perovskite films. Finally, the characteristics of the gate‐modulated light emission are found to conform to a rectified linear unit function, serving as nonlinear electrical‐to‐optical converters in artificial neural networks. Overall, the hot electron engineering approach demonstrated in this work provides effective location‐specific control of the phase and optical properties of halide perovskites, underscoring the potential of plasmonic metasurfaces for advancing perovskite technologies.
Organolead trihalide perovskites have emerged as a new class of competitive solution‐processed semiconductors due to their unique optoelectronic properties. However, poor ambient stability and charge ...transport are the Achilles’ heel of hybrid perovskites, thus limiting their applications. In this work, microwave‐assisted synthesis is applied for the first time to rapidly grow perovskite single crystals embedded with single‐wall carbon nanotubes. These nanotube‐in‐perovskite single crystals are endowed with a carrier mobility one order of magnitude higher than the pure counterpart and the related photodetectors show an ultrafast photo‐response speed (5 and 80 ns for rise and decay time, respectively). The fast and uniform heating of microwave irradiation facilitates the synthesis of ambient‐stable crystals with nanoscale additives, paving the way to creating a wide range of mixed‐dimensional perovskite‐based nanocomposites with optimal properties and device performance.
In this work, microwave‐assisted synthesis is applied to rapidly grow perovskite single crystals embedded with carbon nanotubes as charge transport “highways.” As a result, the mixed‐dimensional single‐crystalline composites feature high carrier mobility of ≈300 cm2 V−1 s−1, accompanied by an ultrafast photo‐response speed of 5 ns, promising as a new material platform for advancing high‐performance perovskite optoelectronics.
Perovskite quantum dots (PQDs) are a competitive candidate for next‐generation display technologies as a result of their superior photoluminescence, narrow emission, high quantum yield, and color ...tunability. However, due to poor thermal resistance and instability under high energy radiation, most PQD‐based white light‐emitting diodes (LEDs) show only modest luminous efficiency of ≈50 lm W−1 and a short lifetime of <100 h. In this study, by incorporating cellulose nanocrystals, a new type of QD film is fabricated: CH3NH3PbBr3 PQD paper that features 91% optical absorption, intense green light emission (518 nm), and excellent stability attributed to the complexation effect between the nanocellulose and PQDs. The PQD paper is combined with red K2SiF6:Mn4+ phosphor and blue GaN LED chips to fabricate a high‐performance white LED demonstrating ultrahigh luminous efficiency (124 lm W−1), wide color gamut (123% of National Television System Committee), and long operation lifetime (240 h), which paves the way for advanced lighting technology.
Perovskite quantum dot paper, a new type of perovskite quantum dot film, is demonstrated. Using a simple, fast, scalable, and inexpensive paper fabrication process, the resulting perovskite quantum dot paper is uniform, of high quality, and very stable; it is able to bear high energy radiation and greatly improve the efficiency of perovskite quantum dot–based white light‐emitting diodes.
Halide perovskite quantum dots (PQDs) are promising materials for diverse applications including displays, light‐emitting diodes, and solar cells due to their intriguing properties such as tunable ...bandgap, high photoluminescence quantum yield, high absorbance, and narrow emission peaks. Despite the prosperous achievements over the past several years, PQDs face severe challenges in terms of stability under different circumstances. Currently, researchers have overcome part of the stability problem, making PQDs sustainable in water, oxygen, and polar solvents for long‐term use. However, halide PQDs are easily degraded under continuous irradiation, which significantly limits their potential for conventional applications. In this study, an oleic acid/oleylamine (traditional surface ligands)‐free method to fabricate perovskite quantum dot papers (PQDP) is developed by adding cellulose nanocrystals as long‐chain binding ligands that stabilize the PQD structure. As a result, the relative photoluminescence intensity of PQDP remains over ≈90% under continuous ultraviolet (UV, 16 W) irradiation for 2 months, showing negligible photodegradation. This proposed method paves the way for the fabrication of ultrastable PQDs and the future development of related applications.
Solid‐state perovskite quantum dot papers are fabricated using a unique vacuum filtration growth method without a purification process. The bonding between cellulose nanocrystals and perovskite quantum dots makes the hybrid structure stable, and record high UV stability and thermal stability are achieved for perovskite quantum dot papers.
Structural defects are ubiquitous for polycrystalline perovskite films, compromising device performance and stability. Herein, a universal method is developed to overcome this issue by incorporating ...halide perovskite quantum dots (QDs) into perovskite polycrystalline films. CsPbBr3 QDs are deposited on four types of halide perovskite films (CsPbBr3, CsPbIBr2, CsPbBrI2, and MAPbI3) and the interactions are triggered by annealing. The ions in the CsPbBr3 QDs are released into the thin films to passivate defects, and concurrently the hydrophobic ligands of QDs self‐assemble on the film surfaces and grain boundaries to reduce the defect density and enhance the film stability. For all QD‐treated films, PL emission intensity and carrier lifetime are significantly improved, and surface morphology and composition uniformity are also optimized. Furthermore, after the QD treatment, light‐induced phase segregation and degradation in mixed‐halide perovskite films are suppressed, and the efficiency of mixed‐halide CsPbIBr2 solar cells is remarkably improved to over 11% from 8.7%. Overall, this work provides a general approach to achieving high‐quality halide perovskite films with suppressed phase segregation, reduced defects, and enhanced stability for optoelectronic applications.
A universal approach is reported to fabricate perovskite films by incorporating inorganic CsPbBr3 quantum dots (QDs) into halide perovskite bulk films. Upon post‐annealing, the released elements from QDs compensate vacancies, and hydrophobic ligands on QDs passivate under‐charged Pb atoms and self‐assemble on surface. Therefore, the resulting films with reduced trap density, suppressed phase segregation, improved surface uniformity and enhanced stability are enabled.
Abstract
Two dimensional inorganic–organic hybrid perovskites (2D perovskites) suffer from not only quantum confinement, but also dielectric confinement, hindering their application perspective in ...devices involving the conversion of an optical input into current. In this report, we theoretically predict that an extremely low exciton binding energy can be achieved in 2D perovskites by using high dielectric-constant organic components. We demonstrate that in (HOCH
2
CH
2
NH
3
)
2
PbI
4
, whose organic material has a high dielectric constant of 37, the dielectric confinement is largely reduced, and the exciton binding energy is 20-times smaller than that in conventional 2D perovskites. As a result, the photo-induced excitons can be thermally dissociated efficiently at room temperature, as clearly indicated from femtosecond transient absorption measurements. In addition, the mobility is largely improved due to the strong screening effect on charge impurities. Such low dielectric-confined 2D perovskites show excellent carrier extraction efficiency, and outstanding humidity resistance compared to conventional 2D perovskites.
The intrinsically poor stability of three-dimensional (3D) α-CsPbI3 perovskites (PVSKs) greatly hinders their application in solar cells and optoelectronics. Here, we propose a new series of ...compounds, quasi-2D Dion–Jacobson (DJ) CsPbI3 PVSKs, through density functional theory (DFT) calculation. The material design is based on periodic intercalation of tailored ethylenediamine cations (EDA2+) between the inorganic layers. The resultant quasi-2D (EDA)Csn−1PbnI3n+1 PVSKs exhibit fundamentally enhanced stability, owing to the strong I–H interaction of diamine cations with a shortened interlayer distance (∼3.5 Å). Their bandgaps can be widely and linearly tailored from 2.150 (n = 1) to 1.476 eV (n = ∞) with the increase of the inorganic layer number (n). In comparison to the conventional 3D counterparts, they have smaller effective masses, lower exciton energies and larger dielectric constants. Furthermore, the highest power conversion efficiency (PCE) is calculated to be 20.9% (n = 50), evidencing that the quasi-2D DJ CsPbI3 PVSKs could be an excellent candidate for exciting applications in optoelectronic devices.
Halide perovskites, such as methylammonium lead halide perovskites (
MAPbX
3
,
X
=
I
, Br, and Cl), are emerging as promising candidates for a wide range of optoelectronic applications, including ...solar cells, light-emitting diodes, and photodetectors, due to their superior optoelectronic properties. All-inorganic lead halide perovskites
CsPbX
3
are attracting a lot of attention because replacing the organic cations with
Cs
+
enhances the stability, and its halide-mixing derivatives offer broad bandgap tunability covering nearly the entire visible spectrum. However, there is evidence suggesting that the optical properties of mixed-halide perovskites are influenced by phase segregation under external stimuli, especially illumination, which may negatively impact the performance of optoelectronic devices. It is reported that the mixed-halide perovskites in forms of thin films and nanocrystals are segregated into a low-bandgap I-rich phase and a high-bandgap Br-rich phase. Herein, we present a critical review on the synthesis and basic properties of all-inorganic perovskites, phase-segregation phenomena, plausible mechanisms, and methods to mitigate phase segregation, providing insights on advancing mixed-halide perovskite optoelectronics with reliable performance.
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