Mixed-dimensional Perovskite Research Articles

Phase transitions in mixed-dimensional perovskite: From film formation evolution to its impact on optoelectronic properties

The integration of 2D/3D mixed-dimensional structures in perovskite solar cells (PSCs) has been demonstrated to substantially improve both their photovoltaic performance and device stability. However, the detailed formation mechanism of these mixed-dimensional perovskite phases remains largely unexplored. In this study, we investigate the in-depth formation evolution of mixed-dimensional perovskite phases using the pre-adding method under both one-step and two-step processing condition, where the HTAB ligand molecule is introduced into the perovskite precursor solution beforehand. In the two-step sequential deposition method, 2D perovskite phases formed sequentially via 2D-α/β/γ (upon the assistance of IPA solvent) → 2D-7.6° (upon thermal annealing) → 2D-7.3° (upon thermal annealing). Conversely, in the one-step method, a distinct progression is noted: 2D-7.6° (HTAB ligand react with intermediate phase) → 2D-7.3°. The 2D-α/β/γ phases exhibit extremely thin, belt-like crystals that cover the 3D perovskite surface, the 2D-7.6° phase trends to envelop the 3D perovskite grains without clear crystal morphology, while the 2D-7.3° phase forms distinct platelet-shaped crystals interspersed among the 3D perovskite grains. Leveraging the defect passivation properties of those mixed-dimensional perovskite phases, as well as improved film morphology and crystallinity adjusted by HTAB ligand, an external electroluminescence quantum efficiency (EQELED) of 13.5 % is achieved in PSCs with a non-radiative voltage loss of just 52 mV, promoting the power conversion efficiency to 24.54 %. This work offers the significant insights into the phase-transition of mixed-dimensional perovskite and their impact on the optoelectronic properties.

Controlled Growth of 2D‐3D Perovskite Lateral Heterostructures for Wavelength‐Tunable Light Communication

AbstractLateral heterostructures based on halide perovskites exhibit great potential in the advancement of next‐generation optoelectronic devices. Among them, mixed dimensional perovskite heterostructures, particularly 2D‐3D ones, offer promising opportunities for semiconductor integration and device miniaturization by combining the advantages of 2D and 3D perovskites. However, the controllable and rapid growth of 2D‐3D halide perovskite lateral heterostructures has not yet been achieved. This study presents an efficient strategy that integrates one‐pot method and space‐confined process to enable liquid‐phase lateral growth of a series of 2D Ruddlesden‐Popper (RP) perovskites on the sides of 3D perovskites. The photodetectors (PDs) based on (BA)2MAn‐1PbnBr3n+1‐MAPbBr3 (n = 1, 2, 3) lateral heterostructures demonstrate outstanding optoelectronic performance, featuring an on/off ratio of up to 1.4 × 104, a high responsivity of 4.4 A W−1 and a detectivity of 3.9 × 1013 Jones at 425 nm, 3 V bias. In addition, by combining the tunable dual‐band photoresponse characteristic with the dual‐beam irradiation modes, a wavelength‐tunable light communication system based on the lateral heterostructure PDs is realized. This work provides a convenient and reliable approach for the direct growth of mixed‐dimensional halide perovskite heterostructures, further demonstrating their potential in high‐performance detecting and dual‐band sensing fields.

New Insights into MAI Additives in 2D-Assisted 3D Controlled Crystallization Toward High-Quality α-Phase FAPbI3 Perovskites.

The highly oriented 2D perovskite templates of n = 1 have typically been created to attain controllable and oriented crystallization of 3D α-phase formamidinium lead triiodide (α-FAPbI3) perovskites. However, the role of methylammonium iodide (MAI), a widely used α-FAPbI3 phase stabilizer, in regulating the growth dynamics of 2D/3D perovskites is generally ignored. Herein, Ruddlesden-Popper type n = 1 2D octylammonium lead iodide(OA2PbI4) perovskites are added into FAPbI3 precursor solution. The template of n = 2 (OA2MAPb2I7), which is spontaneously constructed by the mixture of n = 1 2D and methylammonium chloride (MACl), acts as a skeleton to template the epitaxial growth of α-FAPbI3. However, the volatilization of MACl inevitably causes damage to the 2D structure during thermal annealing. This study reveals that small amounts of less volatile MAI additive enables the creation of stable 2D template, leading to more controlled vertical orientation crystallization. Consequently, the high-quality mixed-dimensional perovskite film delivers a high efficiency of 24.19% together with improved intrinsic stability. This work provides an in-depth understanding of 2D-assisted controlled epitaxial growth of α-FAPbI3.

In Situ Self-Assembled 1D/3D Mixed-Dimensional Perovskite Heterostructures for Efficient White Light Emission.

Mixed-dimensional perovskite (MDP) heterostructures are promising optoelectronic semiconductors. Yet, the current preparation methods involve complex experimental procedures and material compatibility constraints, limiting their widespread applications. Here, we present a one-step room temperature solution-based approach to synthesize a range of 1D C4N2H14PbBr4 and 3D APbBr3 (A = Cs+, MA+, FA+) self-assembled MDP heterostructures exhibiting high-efficiency white light-emitting properties. The ultra-broadband emission results from the synergy between the self-captured blue broadband emission from 1D perovskites and the green emission of 3D perovskites, covering the entire visible-light spectrum with a full width at half-maximum exceeding 170 nm and a remarkable photoluminescence quantum yield of 26%. This work establishes a novel prototype for the preparation of highly luminescent MDP heterostructures, offering insights for future research and industrialization in the realm of white light LEDs.

Resistive switching memories with enhanced durability enabled by mixed-dimensional perfluoroarene perovskite heterostructures.

Hybrid halide perovskites are attractive candidates for resistive switching memories in neuromorphic computing applications due to their mixed ionic-electronic conductivity. Moreover, their exceptional optoelectronic characteristics make them effective as semiconductors in photovoltaics, opening perspectives for self-powered memory elements. These devices, however, remain unexploited, which is related to the variability in their switching characteristics, weak endurance, and retention, which limit their performance and practical use. To address this challenge, we applied low-dimensional perovskite capping layers onto 3D mixed halide perovskites using two perfluoroarene organic cations, namely (perfluorobenzyl)ammonium and (perfluoro-1,4-phenylene)dimethylammonium iodide, forming Ruddlesden-Popper and Dion-Jacobson 2D perovskite phases, respectively. The corresponding mixed-dimensional perovskite heterostructures were used to fabricate resistive switching memories based on perovskite solar cell architectures, showing that the devices based on perfluoroarene heterostructures exhibited enhanced performance and stability in inert and ambient air atmosphere. This opens perspectives for multidimensional perovskite materials in durable self-powered memory elements in the future.

Surface Defect Passivation by 2-(Anthracene-9-carboxamido)ethan-1-aminium Methylammonium in Lead Iodide Mixed-Dimensional Perovskites

Surface Defect Passivation by 2-(Anthracene-9-carboxamido)ethan-1-aminium Methylammonium in Lead Iodide Mixed-Dimensional Perovskites

Synergy of 3D and 2D Perovskites for Durable, Efficient Solar Cells and Beyond.

Three-dimensional (3D) organic-inorganic lead halide perovskites have emerged in the past few years as a promising material for low-cost, high-efficiency optoelectronic devices. Spurred by this recent interest, several subclasses of halide perovskites such as two-dimensional (2D) halide perovskites have begun to play a significant role in advancing the fundamental understanding of the structural, chemical, and physical properties of halide perovskites, which are technologically relevant. While the chemistry of these 2D materials is similar to that of the 3D halide perovskites, their layered structure with a hybrid organic-inorganic interface induces new emergent properties that can significantly or sometimes subtly be important. Synergistic properties can be realized in systems that combine different materials exhibiting different dimensionalities by exploiting their intrinsic compatibility. In many cases, the weaknesses of each material can be alleviated in heteroarchitectures. For example, 3D-2D halide perovskites can demonstrate novel behavior that neither material would be capable of separately. This review describes how the structural differences between 3D halide perovskites and 2D halide perovskites give rise to their disparate materials properties, discusses strategies for realizing mixed-dimensional systems of various architectures through solution-processing techniques, and presents a comprehensive outlook for the use of 3D-2D systems in solar cells. Finally, we investigate applications of 3D-2D systems beyond photovoltaics and offer our perspective on mixed-dimensional perovskite systems as semiconductor materials with unrivaled tunability, efficiency, and technologically relevant durability.

One-pot solution synthesis of 2D-3D mixed-dimensional perovskite crystalline lateral heterostructures

Halide perovskites, owing to their excellent characteristics, have demonstrated huge potential in next-generation optoelectronic applications. Creating perovskite heterostructures, featuring the spatial modulation of physical properties, is expected to further boost device performance and open up new realms; however, direct growth of spatially defined mixed-dimensional lateral heterostructures remains a significant challenge. Here, we present a one-pot solution synthesis of two-three-dimensional (2D-3D) perovskite crystalline lateral heterostructures, leveraging their different temperature-dependent solubilities. A series of lateral heterostructures is demonstrated with well-defined interfaces and clear structural and optical modulations. Benefiting from the built-in field that effectively suppresses the dark current and separates the photogenerated carriers, the proof-of-concept photodetectors yield a low dark current less than 0.01 nA and a champion detectivity exceeding 1013 Jones. The general, facile synthesis of diverse mixed-dimensional perovskite lateral heterostructures provides a versatile hybrid material platform for exploring unique physics and affords new opportunities for advanced perovskite electronics.

Electron Acceptor Molecule Doping Induced π-π Interaction to Promote Charge Transport Kinetics for Efficient and Stable 2D/3D Perovskite Solar Cells.

Although the incorporation of 2D perovskite into 3D perovskite can greatly enhance intrinsic stability, power conversion efficiency (PCE) of 2D/3D perovskite is still inferior to its 3D counterpart due to poor carrier transport kinetics resulted from the quantum and dielectric confinement of 2D component. To overcome this issue, the electron acceptor molecule 1,2,4,5-tetracyanobenzene (TCNB) was introduced to trigger intermolecular π-π interaction in 2D perovskite along with the electronic doping of 2D/3D perovskite to improve charge transfer efficiency. By virtue of high electron affinity, TCNB can undergo electron transfer reaction and subsequently establish π-π interaction with 1-naphthalenemethylammonium (NMA) cations, greatly strengthening lattice rigidity and reducing exciton binding energy. Transmission electron microscopy results demonstrate that 2D phases are mainly distributed at grain boundaries, reducing defect density and weakening nonradiative recombination. Meanwhile, the p-type doping of perovskite by TCNB optimizes energy level alignment at perovskite/hole transport layer interface. Consequently, PCE of champion device is significantly boosted to 24.01 %. The unencapsulated device retains an initial efficiency close to 94 % after exposure to ambient environment for over 1000 h. This work paves a novel path for designing new mixed-dimensional perovskite solar cells with high PCE and superior stability.

Improving the stability and performance of hybrid perovskite solar cells based on 1D/3D mixed-dimensional structure by multiple cation doping

1D-structure perovskite materials have gradually attracted people's attention due to the flexibility of their crystal structures and their strong stability to environments such as water and humidity. In this work, 1D/3D mixed-dimensional perovskite materials were achieved by adding large cation tBA+. The Cs+ doped high quality perovskite films (CstBAMAFA) were prepared by a two-step solution method, and the photoelectrical properties and stability of perovskite solar cells (PSCs) were systematically analyzed. The photoelectric conversion efficiency (PCE) of the champion Cs+ doped 1D/3D PSCs reached 17.08%, and the stability was significantly improved compared with the control group. The PCE of unencapsulated PSCs could retain 80% of the initial value after 197 days of storage in Ar glove box, and 69.3% of the initial value after 20 days of storage at 30 °C with a relative humidity of 50–60%. The improved efficiency and stability of Cs+ doped 1D/3D PSCs are attributed to the filling of the grain boundaries by the 1D phase.

Anisotropic emission of orientation-controlled mixed-dimensional perovskites for light-emitting devices

Perovskite light-emitting diodes (PeLEDs) are attracting increasing attention owing to their impressive efficiencies and high luminance across the full visible light range. Further improvement of the external quantum efficiency (EQE) of planar PeLEDs is limited by the light out-coupling efficiency. Introducing perovskite emitters with directional emission in PeLEDs is an effective way to improve light extraction. Here, we report that it is possible to achieve directional emission in mixed-dimensional perovskites by controlling the orientation of the emissive center in the film. Multiple characterization methods suggest that our mixed-dimensional perovskite film shows highly orientated transition dipole moments (TDMs) with the horizontal ratio of over 88%, substantially higher than that of the isotropic emitters. The horizontally dominated TDMs lead to PeLEDs with exceptional high light out-coupling efficiency of over 32%, enabling a high EQE of 18.2%.

Inorganic frameworks of low-dimensional perovskites dictate the performance and stability of mixed-dimensional perovskite solar cells.

Mixed-dimensional perovskites containing mixtures of organic cations hold great promise to deliver highly stable and efficient solar cells. However, although a plethora of relatively bulky organic cations have been reported for such purposes, a fundamental understanding of the materials' structure, composition, and phase, along with their correlated effects on the corresponding optoelectronic properties and degradation mechanism remains elusive. Herein, we systematically engineer the structures of bulky organic cations to template low-dimensional perovskites with contrasting inorganic framework dimensionality, connectivity, and coordination deformation. By combining X-ray single-crystal structural analysis with depth-profiling XPS, solid-state NMR, and femtosecond transient absorption, it is revealed that not all low-dimensional species work equally well as dopants. Instead, it was found that inorganic architectures with lesser structural distortion tend to yield less disordered energetic and defect landscapes in the resulting mixed-dimensional perovskites, augmented in materials with a longer photoluminescence (PL) lifetime, higher PL quantum yield (up to 11%), improved solar cell performance and enhanced thermal stability (T80 up to 1000 h, unencapsulated). Our study highlights the importance of designing templating organic cations that yield low-dimensional materials with much less structural distortion profiles to be used as additives in stable and efficient perovskite solar cells.

Dimethylammonium Cation-Induced 1D/3D Heterostructure for Efficient and Stable Perovskite Solar Cells.

Mixed-dimensional perovskite engineering has been demonstrated as a simple and useful approach to achieving highly efficient and more-durable perovskite solar cells (PSCs), which have attracted increasing research interests worldwide. In this work, 1D/3D mixed-dimensional perovskite has been successfully obtained by introducing DMAI via a two-step deposition method. The additive DMA+ can facilitate the crystalline growth and form 1D DMAPbI3 at grain boundaries of 3D perovskite, leading to improved morphology, longer charge carrier lifetime, and remarkably reduced bulk trap density for perovskite films. Meanwhile, the presence of low-dimension perovskite is able to prevent the intrusion of moisture, resulting in enhanced long-term stability. As a result, the PSCs incorporated with 1D DMAPbI3 exhibited a first-class power conversion efficiency (PCE) of 21.43% and maintained 85% of their initial efficiency after storage under ambient conditions with ~45% RH for 1000 h.

Whether organic spacer cations induced 2D/3D or quasi-2D/3D mixed dimensional perovskites?

The dimensional engineering of perovskite films has been demonstrated to be an efficient technique to enhance both the efficiency and stability of perovskite solar cells (PSCs). Whether the alternative spacer cations induced 2D/3D or quasi-2D/3D mixed dimensional perovskites make a great difference in the photovoltaic performance and their stability of corresponding PSCs. But the research on this aspect is still insufficient, the crystal structure of the mixed dimensional perovskite is still unclear, which needs more in-depth research. This work adopted the alternative spacer cation of 4-(aminoethyl) pyridine (4-AEP) and the conventional phenylethylamine (PEA), to study their induced low-dimensional crystal phase in 3D perovskite and compare the effect on the performance of corresponding PSCs. We demonstrated that 4-AEP cation has induced 2D crystal phase (low n-value) at the 3D grain boundaries, while the PEA has induced quasi-2D (high n-value) one. As a result, the 4-AEP incorporated MAPbI3 (2D/3D) PSCs obtained a higher power conversion efficiency (PCE, 20.7%) than that of the PEA based quasi-2D/3D ones. More importantly, the 4-AEP based 2D/3D PSCs exhibited better moisture resistance and long-term stability when exposed to moisture and continuous light irradiation. Our work demonstrated that the alternative organic spacer cation could induce 2D or quasi-2D phase in 3D perovskite, but the 2D/3D mixed dimensional perovskite shows more favorable for obtaining highly efficient and stable perovskite solar cells.

0D/2D mixed-dimensional perovskite constructed by thiol- and disulfide-containing ligands

Reduced-dimensional (RD) perovskites have shown attractive chemical and physical properties for optoelectronic applications. Incorporating large organic ligands enables infinite tunability in the components and structures. Theoretically, it is feasible to apply multiple types of organic ligands in a single RD crystal to achieve multiple-dimensional perovskites. However, the coexistence of different organic ligands commonly introduces competing crystal growths that inhibit the formation of a more complex crystal structure. Herein, we report a case of mixed-dimensional (MD) perovskite single crystal containing two types of sulfide-containing ligands. We show that the application of ketones can partially oxidize organothiol ligands in the precursor solution. The resultant disulfide-based ligands can be co-incorporated with the thiol-based ligand in a single MD perovskite crystal. X-ray diffraction confirmed that the structure contains both layered and isolated inorganic components constructed by face-sharing lead halide octahedra. Unlike conventional RD structures, the MD perovskite shows an enlarged bandgap with valence band maximum and conduction band minimum being spatially separated, and isotropic optical features, as revealed by x-ray diffraction, spectroscopies, and density functional theory computation.

Molecularly Controlled Quantum Well Width Distribution and Optoelectronic Properties in Quasi-2D Perovskite Light-Emitting Diodes.

Owing to their excellent optoelectronic properties, quasi-2D perovskites with self-assembled multiple quantum well (MQW) structures have shown great potential in light-emitting diode (LED) applications. Understanding the correlation between the bulky cation, quantum well assembly, and optoelectronic properties of a quasi-2D perovskite is important. Here, we demonstrate that the dipole moment of the bulky cation can be one of the fundamental factors that controls the distribution and crystallinity of different quantum wells. We find that the bulky cation with a moderate dipole moment leads to moderately distributed well-width MQWs, resulting in a superior device efficiency due to the simultaneous achievement of favorable optical and electronic properties. The peak external quantum efficiency and the maximum luminance of the champion device are 10.8% and 19082 cd m-2, respectively, positioning it among the best-performing quasi-2D green perovskite LEDs without further surface passivation or additive doping. This work provides a perspective on the rational design of bulky cations in quasi-2D perovskite LEDs, which is also essential for the development of other mixed-dimensional perovskite optoelectronic devices.

0D–3D mixed-dimensional perovskite Cs4Pb(BrCl)6–CsPbBr2−xCl1+x films for stable and sensitive self-powered, high-temperature photodetectors

0D Cs4Pb(BrCl)6 can suppress the cubic to tetragonal phase transition of 3D CsPbBr2−xCl1+x in 0D–3D mixed-dimensional Cs4Pb(BrCl)6–CsPbBr2−xCl1+x films, enabling high-temperature, self-powered PDs with excellent performance and stability.

Facet orientation tailoring via 2D-seed- induced growth enables highly efficient and stable perovskite solar cells

<h2>Summary</h2> Adding 2D perovskite to 3D perovskite has been developed to effectively enhance the intrinsic stability, but it will inevitably compromise the power conversion efficiency (PCE). Here, in a novel way, we introduced highly oriented 2D (BDA)PbI₄ perovskites as seeds to optimize the growth kinetics of 3D perovskite and make its crystallization directly stride over the nucleation stage. Therefore, the seeds preferentially act as templates to epitaxially grow 3D perovskite with the desired facet orientation and stacking mode. Moreover, the 2D seeds are transformed into the grain boundary after completing the orientation-induced growth. As a result, the high-quality mixed-dimensional perovskite film delivers a superior PCE of 23.95%, accompanied by a remarkable FF of 0.847. The unencapsulated Perovskite solar cell (PSC) retains 93% of its original efficiency after 1,056 h of storage and retains 91% of its initial efficiency after 500 h of operation at the maximum power point under simulated AM1.5 illumination at 60°C.

Dimension tailoring via antisolvent enables efficient perovskite light-emitting diodes

Electroluminescence based on in-situ formed mixed-dimensional perovskites draws increasing attention owing to the rapid progress in device performance. A major challenge in the mixed-dimensional perovskites is the manipulation of the dimension distribution, which is critical for energy transfer efficiency and charge transport. Here, we demonstrate that hybrid antisolvent can tailor the phase distribution by removing excess bulky ammonium cations, leading to the elimination of the quasi-2D perovskites (L2(FAPbBr3)n-1PbBr4, n ≤ 3). The energy transfer efficiency and charge transport are then improved in the tailored film. As a result, the perovskite light-emitting diodes based on the tailored films show decent external quantum efficiency of 16.9% on average and 18.5% for the champion device (emission wavelength: 532 nm), significantly higher than those of the control devices (12.3% and 13.8%, emission wavelength: 527 nm). The hybrid antisolvent approach provides a simple but effective way to tailor the dimension distribution in perovskites, which is essential for high-performance perovskite light-emitting diodes.

Visualizing band alignment across 2D/3D perovskite heterointerfaces of solar cells with light-modulated scanning tunneling microscopy

Graded 2D perovskite capping shells with continuously upshifting valence bands, produced by tailored dimensional engineering, can effectively extract holes from 3D perovskite cores. Real-space observation of electronic structures will fully reveal the operating mechanisms of 2D/3D hybrid perovskite solar cells (PSCs). Here, for the first time, light-modulated scanning tunneling microscopy visualizes the cross-sectional band alignment across 2D (C 4 H 9 NH 3 ) 2 (CH 3 NH 3 ) n-1 Pb n I 3n+1 /3D CH 3 NH 3 PbI 3 stacked perovskites. By systematically analyzing their electronic configuration, the mixed-dimensional perovskite band structure along the vertical 3D-to-2D direction can be spatially resolved. Remarkably, the electric field in the 2D perovskite is larger under light illumination than under dark conditions, resulting in an increase in the concentration of holes and electrons distributed in the 2D and 3D perovskites, respectively. Benefiting from this electronic reconstruction, charge recombination is suppressed, thereby significantly promoting the 2D/3D PSC performance. Moreover, our method opens an avenue for direct, local mapping of optoelectronic device energy levels. • Real spacing energy band distribution of photo-activated 2D/3D perovskites is first mapped. • Visualization of photocarrier dynamics is demonstrated, promote efficiencies of 2D/3D perovskite solar cells. • The electric field in the 2D perovskite is enhanced under light illumination. • This LM-XSTM technology will be used for other semiconductor devices.