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The synergistic utilization of low‐dimensional perovskites with 3D perovskite architectures represents a pervasive approach for fabrication of high‐performance and enduring perovskite solar cells (PSCs). In this work, four distinct ionic liquids (ILs) with distinct cations, were introduced on the surface of 3D perovskite to induce the formation of 1D perovskite.Starting with the analysis of 1D/3D heterojunction structures, the assessment foucsed on the binding energies in four ILs‐induced 1D/3D heterojunctions, comparing electron cloud density within 1D/3D structures, and calculating the formation energies associated with iodine and lead defects within these four 1D/3D perovskite structures via DFT calculations. Furthermore, the time‐resolved grazing‐incidence wide‐angle X‐ray scattering technique, as employed in this study, offers real‐time insights into the phase‐transition occurring during the process of ILs coating and the formation of 1D/3D heterojunctions. The well‐designed and optimized 1D perovskite layer significantly reduces the residual lead iodide (PbI2), modulates the work function of the perovskite, and passivates defects in the 3D perovskite, thereby reducing non‐radiative recombination and enhancing charge transport. With the assistance of 1D/3D hybrid films, we achieved an exceptional power conversion efficiency (PCE) of 24.75% in the generated PSCs with remarkable stability. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are extensively utilized for the manipulation of crystallization kinetics of perovskite, morphology optimization, and defect passivation for the fabrication of highly efficient and stable devices. However, comparing ILs with different chemical structures and selecting the appropriate ILs from the many types available to enhance perovskite device performance remains a challenge. In this study, a range of ILs containing different sizes of anions are introduced as additives for assisting in film formation in perovskite photovoltaics. Specifically, ILs with various sizes significantly affects the strength of chemical interaction between ILs and perovskite composition, inducing varying degrees of conversion of lead iodide to perovskite as well as the formation of perovskite films with markedly disparate grain sizes and morphology. Theoretical calculations in conjunction with experimental measurements revealed that small‐sized anion can more effectively reduce defect density by filling halide vacancies within perovskite bulk materials, resulting in suppression of charge‐carrier recombination, an extended photoluminescence lifetime, and significantly improved device performance. Boosted by ILs with appropriate size, the champion power conversion efficiency of 24.09% for the ILs‐treated device is obtained, and the unencapsulated devices retain 89.3% of its original efficiency under ambient conditions for 2000 h. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have been investigated recently in perovskite photovoltaics owing to their potential to boost optoelectronic performance and device stability. However, the impact of variations in the MOF side chain on perovskite characteristics and the mechanism of MOF/perovskite film formation remains unclear. In this study, three nanoscale thiol‐functionalized UiO‐66‐type Zr‐based MOFs (UiO‐66‐(SH)2, UiO‐66‐MSA, and UiO‐66‐DMSA) are systematically employed and examined in perovskite solar cells (PSCs). Among these MOFs, UiO‐66‐(SH)2, with its rigid organic ligands, exhibited a strong interaction with perovskite materials with more efficient suppression of perovskite vacancy defects. More importantly, A detailed and in‐depth discussion is provided on the formation mechanism of UiO‐66‐(SH)2‐assisted perovskite film upon in situ GIWAXS performed during the annealing process. The incorporation of UiO‐66‐(SH)2 additives substantially facilitates the conversion of PbI2 into the perovskite phase, prolongs the duration of stage I, and induces a delayed phase transformation pathway. Consequently, the UiO‐66‐(SH)2‐assisted device demonstrates reduced defect density and superior optoelectronic properties with optimized power conversion efficiency of 24.09% and enhanced long‐term stability under ambient environment and continuous light illumination conditions. This study acts as a helpful design guide for desired MOF/perovskite structures, enabling further advancements in MOF/perovskite optoelectronic devices. [ABSTRACT FROM AUTHOR]

Highlights: High-quality Sn2+/Mn2+-co-doped Rb4CdCl6 single crystals and powders were prepared and showed high-performance dual-emission white light with near-unity photoluminescence quantum yield. Short-range and extremely strong interactions between Sn2+ and Mn2+ were observed that lead to an intriguing ultra-high-efficiency Dexter energy transfer process from adjacent Sn2+ ions to Mn2+ ions. The dual-emission intensities were tuned flexibly by varying the fractions of Sn2+ and Sn–Mn pairs to balance their emission proportions for cold/warm white-light generation. Single materials that exhibit efficient and stable white-light emission are highly desirable for lighting applications. This paper reports a novel zero-dimensional perovskite, Rb4CdCl6:Sn2+, Mn2+, which demonstrates exceptional white-light properties including adjustable correlated color temperature, high color rendering index of up to 85, and near-unity photoluminescence quantum yield of 99%. Using a co-doping strategy involving Sn2+ and Mn2+, cyan-orange dual-band emission with complementary spectral ranges is activated by the self-trapped excitons and d-d transitions of the Sn2+ and Mn2+ centers in the Rb4CdCl6 host, respectively. Intriguingly, although Mn2+ ions doped in Rb4CdCl6 are difficult to excite, efficient Mn2+ emission can be realized through an ultra-high-efficient energy transfer between Sn2+ and Mn2+ via the formation of adjacent exchange-coupled Sn–Mn pairs. Benefiting from this efficient Dexter energy transfer process, the dual emission shares the same optimal excitation wavelengths of the Sn2+ centers and suppresses the non-radiative vibration relaxation significantly. Moreover, the relative intensities of the dual-emission components can be modulated flexibly by adjusting the fraction of the Sn2+ ions to the Sn–Mn pairs. This co-doping approach involving short-range energy transfer represents a promising avenue for achieving high-quality white light within a single material. [ABSTRACT FROM AUTHOR]

Mixed‐dimensional engineering of perovskite material has been demonstrated as a facile and promising strategy to improve both photovoltaic performance and long‐term stability of perovskite solar cells (PSCs). In this study, we report an in‐plane preferred orientation of 1D perovskite induced by an ionic liquid (IL) of 1‐(3‐cyanopropyl)‐3‐methylimidazolium chloride (CPMIMCl) for the first time via sequential deposition approach, leading to a mixed dimensional perovskite thin films. The generated one‐dimensional (1D) CPMIMPbI3 with in‐plane orientation resides at the grain boundaries of three‐dimensional (3D) perovskite can be appreciably observed from the morphology level, leading to creation of high‐quality films with large grain size with more efficient defect passivation. Moreover, the dispersion of IL in the bulk phase of perovskite material allows for the formation of 1D perovskite for multiple level passivation to inhibit non‐radiative recombination and optimize carrier transport. This IL engineering strategy not only yields a mixed‐dimensional perovskite heterostructure with in‐plane orientation 1D perovskite nano‐rods but also significantly improves the opto‐electronic property with suppressed trap states. As a result, the CPMIMCl‐treated PSCs show an enhanced photovoltaic performance with a champion power conversion efficiency (PCE) up to 24.13%. More importantly, benefiting from the hydrophobicity of formed 1D perovskite and defects suppression, the corresponding PSC demonstrates an excellent long‐term stability and maintain 97.1% of its pristine PCE at 25°C under 50% RH condition over 1000 h. This research provides an innovative perspective for employing the low dimensional engineering to optimize the performance and stability of photovoltaic devices. [ABSTRACT FROM AUTHOR]

Metal halide perovskites can be readily synthesized, they exhibit tunable physical properties and excellent performance, and they are heavily studied optoelectronic materials. Compared to the typical three-dimensional perovskites, morphological-level one-dimensional (1D) nanostructures enable charge transport and photon propagation with low exciton binding energies and long charge-carrier diffusion lengths, while molecular-level 1D nanostructures exhibit good compositional and structural flexibilities, highly tunable bandgaps, strong quantum confinement effects, and excellent ambient stabilities. The 1D natures of these emerging halide perovskites enhance the performance of optoelectronic devices. Herein, we highlight recent progress realized in the syntheses and characterizations of both morphological- and molecular-level 1D halide perovskites with tunable structures, compositions, and properties, as well as their photovoltaic, light-emission, and photodetection applications. In addition, current challenges, future prospects, and promising research directions are discussed to provide guidance in advancing the field of 1D perovskites. The recent advances realized in the syntheses and characterizations of both morphological- and molecular-level one-dimensional (1D) metal-halide perovskites with tunable structures, compositions, and properties, as well as optoelectronic applications are comprehensively reviewed. Furthermore, the challenges, prospects, and promising research directions are discussed, which we believe will help to accelerate the explorations of 1D metal-halide perovskites in the future. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are promising optoelectronic materials due to their unique luminescent properties. However, their practical application is limited by their poor chemical stability, especially in humid environments. Moisture can cause phase changes or chemical decomposition, resulting in significant fluorescence quenching. In this study, a copper‐based organic–inorganic hybrid metal halide (t‐BA)3Cu6I9 is synthesized (t‐BA+ is the tert‐butyl‐ammonium ion (C(CH3)3NH3+)). This material exhibits water‐induced luminescence, and its chemical stability in humid environments is being investigated. Tetragonal t‐BA3Cu6I9 is not luminescent, but it reacts quickly with water in the air. The resultant (t‐BA)2Cu2I4·H2O has a broad green emission peak at 520 nm, high photoluminescence quantum yield of 59.4%. Remarkably, (t‐BA)2Cu2I4·H2O is converted back to t‐BA3Cu6I9 at temperatures above 40 °C. This phase conversion is highly repeatable, and the luminescent intensity can be fully recovered after 50 transformation cycles. The mechanism of luminescence is investigated through temperature‐dependent photoluminescence spectra and theoretical calculation, which suggests that (t‐BA)2Cu2I4·H2O has a more localized charge distribution and sufficient polyhedral distortion, resulting in a bright and efficient emission from self‐trapped excitons. This is the first report of water‐induced luminescence in copper‐based metal halides, and it paves the way for stable luminescent materials that are responsive to humidity. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) are promising materials for a range of optoelectronic applications owing to their unique structures and optical properties. The photoluminescence (PL) property of MHPs is crucial for their applications. All‐inorganic MHPs such as CsPbBr3, CsPb2Br5 and Cs4PbBr6, have been widely investigated due to their high PL quantum yield (QY). However, the PL mechanisms of these perovskites still remain controversial and lack a unifying explanation. In this review, we have summarized the recent efforts to reveal the emission process of all‐inorganic cesium lead bromide perovskites nanocrystals (NCs) by utilizing single particle spectroscopy. The recent research advances on the understanding of exciton nature in CsPbBr3 and PL emission originating from intrinsic point defects or impurity CsPbBr3 phase in CsPb2Br5 and Cs4PbBr6 are summarized. Understanding the relationship between the structure and associated PL property of MHPs paves the way for their potential applications. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of inverted perovskite solar cells (PSCs) is often hindered by trap‐induced non‐radiative recombination and photochemical degradation occurring at the upper interfaces and the grain boundaries of perovskite films. Herein, ortho‐, meta‐, and para‐isomers of fluorophenylethylammonium iodine (F‐PEAI) organic spacer molecules are evaluated for the construction of perovskite quantum wells (2D or quasi‐2D, PQWs) to encapsulate 3D perovskites. Among the three variants, p‐F‐PEAI leads to the most symmetric charge distribution and the weakest steric hindrance which resulting in reinforced interactions with PbI2 and perovskite, the enhanced out‐of‐plane orientation is confirmed by Grazing incidence wide‐angle X‐ray scattering (GIWAXS) results. Density functional theory and crystal orbital Hamilton population (COHP) calculations further confirm that p‐F‐PEAI engages most strongly with the perovskite structure. Moreover, transmission electron microscopy (TEM) characterization is used to illustrate that p‐F‐PEAI‐assisted 2D PQWs effectively passivate both the grain boundaries and surfaces of perovskites. This configuration facilitates effective surface passivation, improves charge carrier transport, and significantly suppresses non‐radiative recombination. The resultant inverted PSCs achieve an excellent power conversion efficiency (PCE) of 25.03% with a fill factor (FF) of 85.11%. The unencapsulated devices exhibit enhanced long‐term stability under ambient environments and continuous light illumination. [ABSTRACT FROM AUTHOR]

Large size high‐quality perovskite single‐crystals are highly desirable for investigating their fundamental materials properties and realizing state of the art electronic/optoelectronic device performance. Herein, a novel single‐crystal growth method is reported by recrystallization of perovskites in oversaturated solutions. Perovskite single crystals including both organic–inorganic hybrid metal halides and their all‐inorganic counterparts can be obtained in large amounts by this method. All of the synthesized perovskite single crystals exhibit large crystal sizes (centimeter level) and exceptional light emission properties. Meanwhile, the single‐crystal growth can be well controlled and the solvent can be reused for cycles of single‐crystal growth, which sheds light on the preparation of perovskite materials in a way of green chemistry. In addition, thermodynamic growth principles for the single‐crystal growth are proposed, providing a universal approval for metal halide single‐crystal synthesis. [ABSTRACT FROM AUTHOR]

We prepared high-performance photoresistors based on CH3NH3PbI3 films with a high PbI2 doping level. The role of PbI2 in CH3NH3PbI3 perovskite thin film was systematically investigated using scanning electron microscopy, X-ray diffraction, time-resolved photoluminescence spectroscopy, and photoconductive atomic force microscope. Laterally-structured photodetectors have been fabricated based on CH3NH3PbI3 perovskite thin films deposited using precursor solution with various CH3NH3I:PbI2 ratios. Remarkably, the introduction of a suitable amount of PbI2 can significantly improve the performance and stability of perovskite-based photoresistors, optoelectronic devices with ultrahigh photo-sensitivity, high current on/off ratio, fast photo response speed, and retarded decay. Specifically, a highest responsivity of 7.8 A/W and a specific detectivity of 2.1 × 1013 Jones with a rise time of 0.86 ms and a decay time of 1.5 ms have been achieved. In addition, the local dependence of photocurrent generation in perovskite thin films was revealed by photoconductive atomic force microscopy, which provides direct evidence that the presence of PbI2 can effectively passivate the grain boundaries of CH3NH3PbI3 and assist the photocurrent transport more effectively. [ABSTRACT FROM AUTHOR]

• In-depth mechanism of UiO-66-assisted perovskite film formation by two-steps. • The addition of UiO-66 resulted in porous structure of PbI 2 film. • UiO-66 improved device durability by intensified interaction of Pb-I bonds. • The UiO-66-assisted devices deliver efficiency up to 23.05%. The complete conversion of PbI 2 into high-grade perovskite material with less trap-state density and long-term durability still remains challenging for two-step perovskite photovoltaics. In this work, nanoscale UiO-66, as a classical Zr-MOFs with respectable stability and high specific surface area, has been innovatively introduced into the PbI 2 layer to facilitate the conversion process by morphology tuning and also ultimately improve the durability of the resultant perovskite photovoltaic devices. The added UiO-66 has impressively changed the morphology of PbI 2 film from a pristine compact one into a porous structure, providing better contact with organic salt during second-step deposition, consequently benefitting the thorough and uniform perovskite conversion process. Importantly, the addition of UiO-66 has effectively suppressed the halide vacancies formation due to the increased halide vacancy formation energy at the interface, as evidenced by density functional theory (DFT) calculation, leading to noticeably enhanced charge transport property and greatly improved optoelectronic property. Furthermore, the crystal orbital Hamilton population (COHP) calculation result directly proves that the incorporation of UiO-66 has enhanced the stability of perovskite materials by intensifying the bonding interaction of Pb-I bonds at the interface. Consequently, the UiO-66-assisted devices deliver a champion power conversion efficiency of 23.05% with noticeably improved stability, significantly outperforming the pristine devices. This work demonstrates the brightening potential of MOFs to assist the consequential manufacture of highly efficient and stable perovskite solar cells for upscaling process and deployment in the near future. [ABSTRACT FROM AUTHOR]