Hybrid Organic-inorganic Metal Halide Research Articles

(CH3)2NH2]2PdBr4, a layered hybrid halide perovskite semiconductor with improved optical and electrical properties.

Inspired by the success of three-dimensional hybrid perovskites (CH3NH3)PbX3 (X = Cl, Br, I), two-dimensional (2D) organic-inorganic hybrid metal halides have drawn immense attention due to their highly tunable physical properties. Moreover, although 3D hybrid perovskite materials have been reported, the development of new organic-inorganic hybrid semiconductors is still an area in urgent need of investigation. Here, we used the dimethylammonium cation to construct a palladium-based halide perovskite material [(CH3)2NH2]2PdBr4 with a 2D layered structure. This layered perovskite undergoes one endothermic peak at 415 K corresponding to melting of the organic molecule. The thermal stability of the compound is up to about 500 K. The activation energy and conduction mechanisms are discussed, and the optical study shows a gap energy equal to 2.5 eV. The electrical AC conductivity is in the order of 10-4 Ω-1 cm-1, which confirms the semiconductor character of this material and indicates its importance in the optoelectronic domain.

Second harmonic generation from symmetry breaking stimulated by mixed organic cations in zero-dimensional hybrid metal halides.

Mixing cations with different chemical properties to induce the generation of asymmetric structures is a new approach for tuning the optical properties of hybrid organic-inorganic metal halides (HOIMHs). In this study, zero-dimensional (C9N3H15)(C9H13SO)MBr6 (M = Bi/Sb, [C9N3H15]2+ = [(C4N2H10)(C5NH5)]2+ and [C9H14SO]+ = [CH3(C6H4)OS(CH3)2]+) are synthesized. Two different cations cause both compounds to crystallize in the polar space group P212121, thus resulting in significant phase matchable second harmonic generation under a 1064 nm laser excitation. Thus, (C9N3H15)(C9H13SO)BiBr6 and (C9N3H15)(C9H13SO)SbBr6 exhibit intensities that are approximately 1.8 and 1.7 times that of KH2PO4, respectively. The results of density functional theory calculations show that both (C9N3H15)(C9H13SO)BiBr6 and (C9N3H15)(C9H13SO)SbBr6 exhibit direct bandgaps of 2.95 and 2.81 eV, respectively. Additionally, because of the distortion of the inorganic octahedra, (C9N3H15)(C9H13SO)SbBr6 exhibited bright yellow emission at room temperature, which is attributed to ns2 fluorescence emission. We believe that the symmetry of the HOIMH crystal structure can be broken by introducing spatially differentiated bifunctional organic cations, which consequently enables even-order nonlinear activities.

Lead-free hybrid indium perovskites with near-unity PLQY and white light emission using an Sb3+doping strategy

A series of new Sb3+ doped-(DETA)InCl6 organic–inorganic hybrid metal halide single crystals were synthesized. The PLQY of single crystals doped with 10% Sb was up to 100%, and white light emission was achieved when the Sb doping amount was 0.005%.

Regulation and application of organic luminescence from low-dimensional organic–inorganic hybrid metal halides

In this review, the organic luminescence properties of low-dimensional organic–inorganic hybrid metal halides (LDMHs) are summarized, with emphasis on the mechanism, regulating strategy and applications of organic luminescence in LDMHs.

Regulation strategy of white emission from organic–inorganic hybrid metal halide perovskites

In this review, the structure, photophysical properties, and white-light mechanism of organic–inorganic hybrid metal halide perovskites with white emission are summarized, with an emphasis on the adjustment strategy for white-light performance.

Halogen-regulating induced reversible high-temperature dielectric and thermal transitions in novel layered organic-inorganic hybrid semiconducting crystals.

Organic-inorganic hybrid metal halides for high-temperature phase transition have become increasingly popular owing to their wide operating temperature range in practical applications, e.g., energy storage, permittivity switches and opto-electronic devices. This paper describes the subtle assembly of two new hybrid perovskite crystals, [Cl-C6H4-(CH2)2NH3]2CdX4 (X = Br 1; Cl 2), undergoing high-T reversible phase transformations around 335 K/356 K. Differential scanning calorimetry (DSC), differential thermal analysis (DTA) and VT PXRD tests uncover their reversible first-order phase transition behaviors. Furthermore, the compounds exhibit switchable dielectricity near T, making them potential dielectric switching materials. Hirshfeld surface analysis well discloses a distinct difference in hydrogen-bonding interaction between 1 and 2. UV spectra and computational analysis demonstrate that the compounds are a type of direct-band-gap semiconductor. This research will contribute an effective approach to the structure and development of multifunctional molecular hybrid crystals.

Zero-dimensional organic-inorganic hybrid manganese bromide with coexistence of dielectric-thermal double switches and efficient photoluminescence.

Zero-dimensional (0D) hybrid metal halides have attracted much attention due to their rich composition, excellent optical stability, large exciton binding energy, etc. Photoelectric switchable multifunctional materials can integrate multiple physical properties (e.g., ferroelectricity, photoluminescence, magnetic, etc.) into one device and are widely used in many fields such as smart switches, sensors, etc. However, multifunctional materials with thermal energy storage, stimulant dielectric response, and light-emitting properties are rarely reported. Here, we synthesized a new organic-inorganic hybrid metal halide single crystal [TEMA]2MnBr4 (1) (TEMA+ = triethylmethylammonium). Compound 1 undergoes a reversible phase transition at a high temperature of 344/316 K, having a large thermal hysteresis of 28 K and exhibits high stability dielectric switching characteristics near the phase transition temperature. The single crystal exhibits green emission at 513 nm under UV excitation, originating from the 4T1g(G) → 6A1g(S) transition of Mn2+ ions. Excitingly, this single crystal's photoluminescence quantum yield (PLQY) is as high as 80.78%. This work provides a strategy for the development of organic-inorganic hybrid optoelectronic multifunctional materials with high-efficient light emission and switchable dielectric properties.

Solution Synthesis, Photophysical Properties and Photoelectric Application of Zero-dimensional Organic-inorganic Hybrid Metal Halide

Solution Synthesis, Photophysical Properties and Photoelectric Application of Zero-dimensional Organic-inorganic Hybrid Metal Halide

Performance and stability enhancement of perovskite photodetectors by additive and interface engineering using a dual-functional PPS zwitterion.

Hybrid organic-inorganic metal halide perovskites (HOIPs) have gained significant research interest due to their tunable optoelectronic properties and ease of fabrication. Enhancing the stability and efficiency of perovskite materials can be achieved through the passivation of defective surfaces and the improvement of interfacial properties. In this study, we introduce a zwitterionic compound, PPS (3-(1-pyridinio)-1-propanesulfonate), as a bifunctional material that serves as an additive and an interlayer. Incorporating PPS into the perovskite film effectively reduces both positively and negatively charged defects, leading to improved surface morphology and a reduction in undesired charge carrier recombination. Additionally, the formation of a PPS interlayer on SnO2 improves the SnO2/perovskite interfacial characteristics, thereby enhancing charge carrier extraction. As a result, the photodetector exhibits a low dark current of 6.05 × 10-11 A, an excellent responsivity of 5.93 A W-1, a detectivity of 1.51 × 1013 J, and an on/off ratio of 1.2 × 104 under open-air conditions. Moreover, the device demonstrates outstanding stability, retaining 80% of its original responsivity in an ambient environment. This work highlights the great potential of dual-functional materials for defect passivation in future optoelectronic devices, emphasizing the importance of surface modification and interface engineering for improved performance and stability.

Stabilized Preparation of Fiber-Shaped Perovskite Solar Cells with Ti and Graphene Substrates

Organic–inorganic hybrid metal halide perovskite solar cells (PSCs) have made dramatic progress over the past few years. Fiber-shaped PSCs (FPSCs) extend the application of PSCs to wearable and portable electronics. The one-dimensional flexible structure of the fiber substrate and the high efficiency photoelectric conversion ability of the perovskite materials make FPSCs promising for energy applications. However, FPSCs have limited preparation methods and show poorer optoelectronic performance compared to conventional PSCs. In our work, we present a multiple quantitative coating preparation method, which was optimized by controlling the PbI2 concentration and the cycle number of coating process. We demonstrated the effectiveness of the methods in improving the film performance, with a photoelectric conversion efficiency (PCE) of 5.2% under air. The applicability of the multiple quantitative coating methods was studied by the FPSCs fabricated on reduced graphene fibers (rGFs), which present PCEs of about 1.5%. In addition, by extending the length of rGFs, the device performance was further improved. Thus, we demonstrated a stable fabrication method of FPSCs based on rGFs, which exhibited significant potential for using PSCs as a power source in wearable devices.

Blue Light-Excitable Broadband Yellow Emission in a Zero-Dimensional Hybrid Bismuth Halide with Type-II Band Alignment

Zero-dimensional (0D) organic-inorganic hybrid metal halides have captured broad interest in the lighting and display fields because of their unique electronic structures and splendid broadband emission properties. However, the blue light-excitable broadband yellow emissions have been rarely reported in 0D hybrid metal halides. Here, we design a new 0D bismuth hybrid, (4cmpyH)2BiCl5 (1, 4cmpy = 4-(chloromethyl)pyridine), featuring isolated edge-sharing bioctahedral [Bi2Cl10]4- dimers surrounded by rigid, conjugated, and luminescent organic [4cmpyH]+ cations. This material is able to show intrinsic broadband yellow emissions under blue light (468 nm) excitation with a long lifetime of 22.33 μs and a photoluminescence (PL) quantum yield of 5.56%. Solid-state UV-vis spectroscopy studies prove that introducing organic π-conjugated groups into hybrid systems leads to absorption in the visible light region, in favor of photoexcitation by visible light. By comparing the PL data of 1 and the organic template at room temperature and measuring variable-temperature PL spectra of 1, the blue light-excited broadband emission of 1 can be attributed to the synergistic emissions of intramolecular π → π* and n → π* transitions in the organic cations and triple self-trapped exciton (STE) states centralized at the highly distorted Bi-Cl lattices. Moreover, density functional theory calculations reveal a type-II band alignment in 1 with an indirect band gap of 2.64 eV, which is together determined by organic cations and inorganic bioctahedral units. To the best of our knowledge, our work represents the first report on the blue light-excitable STE emission in 0D Bi-based metal halides, which will largely promote the rapid development of novel high-performance yellow light-emitting materials.

A novel Cd-based multifunctional high temperature phase transition material: [(CH2CH3)3NCH2Cl]2CdBr4

Organic-inorganic hybrid metal halides have attracted considerable attention due to their interesting chemical variability and structure–property flexibility, with remarkable multifunctional properties, including tunable physical, chemical, optical, and electronic properties. However, with the continuous development and change of the social environment, the demand for multifunctional materials is more urgent. In this paper, a new low-dimensional cadmium-based hybrid metal halide multifunctional material with high temperature reversible phase transition is reported: [(CH2CH3)3NCH2Cl]2CdBr4 (1), which exhibits an ultrahigh temperature reversible phase transition at Tc = 421 K variable, and has semiconductor and photoluminescence multifunctional materials. This will stimulate further interest in molecular materials with desirable multifunctional properties.

How Low Can You Go? Defect Quantification at the 1015 cm–3 Level in Mixed-Cation Perovskites Using Differential Pulse Voltammetry

Reactive defects in hybrid organic–inorganic metal halide perovskites that limit material functionality and durability, factors which ultimately dictate (opto)electronic device performance, are difficult to probe. Herein, we expand an electrochemical methodology for near-valence defect quantification, using a solid-state electrolyte “top contact,” to increase energy resolution and sensitivity via a differential pulse protocol. A new low level of detection of ca. 2 × 1015 cm–3 is reported for reactive defects in a triple-cation system. We confirmed that these defects are associated with mobile iodide ions in grain boundaries and at interfaces by using iodide and bromide spiked electrolytes. The detection limit for this electrochemical method is estimated to be ca. 1014 cm–3, well below that of many electrical or spectroscopic approaches. We predict this methodology lends itself to operando defect characterization during and after processing, at scale, of extremely low defect density perovskites and related optoelectronic platforms, ultimately providing an in-line approach to real-time performance and stability optimization.

Large-Area Laminar TEA2MnI4 Single-Crystal Scintillator for X-ray Imaging with Impressive High Resolution.

Current X-ray imaging scintillators are dominated by inorganic scintillators grown through a high-temperature process. Exploring new types of scintillators with mild growth conditions, high light yields, and eco-friendly chemical compositions is essential and challenging. Herein, the zero-dimensional large-area laminar organic-inorganic hybrid metal halide TEA2MnI4 (TEA = tetraethylammonium) single crystal with dimensions of 50 mm × 60 mm × 0.82 mm is grown via a local-heating solvent evaporation method. Compared with its Cl- and Br-based counterparts, the incorporation of the iodine component enhances the X-ray attenuation ability and significantly accelerates the decay of the photoluminescence of TEA2MnI4. Interestingly, the prepared TEA2MnI4 exhibits a high transmittance of >90% over the range of 515-765 nm and exhibits a high light yield of 26288 photons/MeV, which provides the prerequisite for high-resolution X-ray imaging. The TEA2MnI4 single-crystal scintillator displays an astonishing spatial resolution exceeding 25 line pairs per millimeter, which provides a design concept for a Mn-I-based single crystal for high-performance scintillator applications.

Amorphous TiO2 film with fiber like structure: An ideal candidate for ETL of perovskite solar cells

• E T L A m o r p h o u s T i O 2 was prepared by DCP-MS at room temperature. • Lots fiber like structures run through the E T L A m o r p h o u s T i O 2 directly. • Fiber like structures in E T L A m o r p h o u s T i O 2 improves electron transfer efficiency. • PCE of PSCs improves from 4.7% of E T L A n a t a s e T i O 2 to 11.5% of E T L A m o r p h o u s T i O 2 . Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) with planar heterojunction structures were fabricated. The amorphous and anatase TiO 2 electron transfer layer (ETL) was deposited by the direct current pulsed magnetron sputtering technology. With the ordinary CH 3 NH 3 PbI 3 , PSCs with amorphous and anatase TiO 2 ETL showed the average power conversion efficiency in (11.5 ± 0.7)% and (4.7 ± 1.5)%, respectively. Combining with XRD and TEM results, the fiber like structure in amorphous TiO 2 ETL resulted in the increase of average power conversion efficiency of PSCs. Finally, amorphous TiO 2 with fiber like structure is an ideal ETL for PSCs, which is prepared by sputtering.

CTAB assisted solvent-free mechanosynthesis of MAPbX3 nanocrystals: Stability, and photoresponse

In this study, we have used only multifunctional cetyl trimethylammonium bromide (CTAB) with a mechano-synthesis approach, which involves hand grinding to grow hybrid organic-inorganic metal halide perovskite, HPs, (MAPbX3, X ​= ​Br, I). Simplicity, swiftness, reproducibility, and harmony with green chemistry credentials make the mechano-synthesis process a preferable approach to the synthesis of HPs. We have prepared HPs using an equimolar amount of MAX and PbX2 with a mmol amount of CTAB. Steady-state photoluminescence, X-ray diffraction (XRD), and time correlate single-photon count (TCSPC) were performed to investigate the optical and structural features of mechanochemically produced perovskite. The thermogravimetric analysis informs about the thermal stability of the nanocrystals. X-ray diffraction analysis reveals that mechanochemically synthesized HPs show high crystallinity and phase purity with stability over a period of time. The photoinduced current response of the perovskite reveals an excellent increase in photoconductivity when exposed to light (with a 1 ​V bias). The device fabricated of perovskite witnessed the prompt photoresponse under light illumination and temporally-stable photocurrent over the multiple cycles of light irradiation. The synthesized materials are useful for photovoltaic applications because of their phase purity, low bandgap, nanoscale size, long-term stability, and easy-to-produce approach.

Improving the performance of perovskite solar cells via TiO2 electron transport layer prepared by direct current pulsed magnetron sputtering

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) with planar heterojunction structures were fabricated. The traditional methylammonium lead iodide (CH3NH3PbI3, MAPbI3) was selected as the photovoltaic convert layer. The TiO2 electron transport layer (ETL) was prepared by the sol-gel and direct current pulsed magnetron sputtering (DC-PMS) technologies. PSCs with Sol-gel and DC-PMS TiO2 ETLs showed power conversion efficiencies of 13.4% and 16.1%, respectively. The detailed measurement results showed that the DC-PMS TiO2 ETL contained high-density chain-like structures, which consisted of nanosized anatase TiO2 nuclei. Compared with the short-circuit current of 20.08 mA/cm2 for PSCs with Sol-gel TiO2 ETL, the chain-like structure in the DC-PMS TiO2 ETL could effectively improve the short-circuit current to 22.11 mA/cm2. In addition, compared with the hysteresis index of 38.5% for PSCs with Sol-gel TiO2 ETL, the chain-like structure and higher surface potential of the DC-PMS TiO2 ETL could effectively reduce the hysteresis index to 14.9%. Finally, because of the whole room temperature preparation process, DC-PMS technology is an ideal candidate for flexible application of PSCs, which could be applied to the organic substrate without resistance to high temperature.

White Light-Emitting Diodes Based on One-Dimensional Organic-Inorganic Hybrid Metal Chloride with Dual Emission.

White-light emissive organic-inorganic hybrid metal halides (MHs) have shown promising potential applications in solid-state lighting. As one-dimensional (1D) MHs for white-light emission remain rare and the key role of halogen regulation in 1D hybrid MHs for broadband emission (BE) has not been well established yet, herein, we report a family of 1D hybrid MHs TMGPbX3 (TMG = 1,1,3,3-tetramethylguanidine, X = Cl-, Br-, or I-) to systematically explore the influence of halogen on crystal structures and photoluminescence (PL) properties in 1D organic-inorganic hybrid MHs. Under ultraviolet excitation, TMGPbBr3 and TMGPbI3 exhibit BE originating from self-trapped excitons (STEs), while TMGPbCl3 manifests the special blue-white dual emission, which is contributed by STEs in inorganic frameworks and free excitons (FEs) in the organic component. Different emission mechanisms of three 1D MHs are well demonstrated and compared. With a PL quantum yield (PLQY) up to 11.67%, a white light-emitting diode (WLED) based on TMGPbCl3 was fabricated to show its valuable application in solid-state lighting.

Induction of Chiral Hybrid Metal Halides from Achiral Building Blocks.

Chiral hybrid organic-inorganic metal halides (HOMHs) with intrinsic noncentrosymmetry have shown great promise for broad applications in chiroptoelectronics, spintronics, and ferroelectronics. However, the construction strategies for chiral HOMHs often involve chiral building blocks in their frameworks, which greatly limit their chemical diversity. Here, we take advantage of a chiral induction approach and have successfully constructed a series of chiral HOMHs, DMA4MX7 (DMA = dimethylammonium, M = Sb or Bi, X = Cl or Br), based on achiral precursors. The resulting chiral products demonstrate a clear enantioenrichment, as confirmed by single-crystal X-ray diffraction analysis and solid-state circular dichroism (CD) spectroscopy. The induction of chiral HOMHs enables superior nonlinear optical performances with very high thermal stability and laser resistance. The successful employment of such a chiral induction approach might facilitate the construction of libraries of chiral HOMH crystals from diverse achiral precursors, in particular those into which it is not easy to introduce intrinsic chiral centers, and would thus pave a new way for rational preparation and application of chiral HOMH materials.

Factors influencing halide vacancy transport in perovskite solar cells

Ion migration in inorganic and hybrid organic-inorganic metal halide perovskites causes unusual phenomena in photovoltaic devices, such as current-voltage hysteresis and photoinduced phase transformations. It is now well established that metal halide perovskites are mixed ionic-electronic conductors and halide ions are mobile at room temperature. The effect of various physical stimuli like light, heat, pressure, and applied bias can affect the distribution and movement of ions. However, the impact of each stimulus is not understood as the measured response includes a combination of factors. We explore, using first-principles density functional theory (DFT), halide migration mediated by vacancies in model cubic phases of CsPbX3 (X = Cl, Br, I) and systematically control the electronic, chemical, and mechanical conditions. We assess the potential energy landscape for ion migration and how device-relevant conditions and compositional engineering can influence the physical behaviour of halide perovskites.