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abbreviated as AMX 3 (A is an organic cation, e.g., CH 3 NH 3 + , HN=CHNH 3 + ; M is a metal cation, e.g., Sn 2+ , Pb 2+ ; X is a halide anion, e.g., Cl − , Br − , I −). In their crystal framework, corner-sharing BX 6 octahedrons form the 3D network with the A cations situated in the cuboctahedral interstices. [4,5] The inorganic components of the halide perovskite provide the conductive backbones required by the carrier's ordered transmission and also provide the thermal and mechanical stability of the material. The organic components, on the other hand, function as templates via hydrogen bonds during the perovskite film formation process. Different from 3D perovskites, layer-structured 2D perovskite materials follow the (RNH 3) 2 (A 3) n-1 M n X 3n+1 structure, where R is an alkyl or aromatic moiety larger than A, and n is the number of inorganic layers between the organic chains. [6,7] When n→∞, the structure converts to 3D perovskite. When n is a limited integer, quantum well structures form with layers of AX 4 2− separated and supported by a layer of organic cations via weak van der Waals forces. The inorganic components provide high carrier mobility and wide bandgap tunability. The organic components, being either large aliphatic or aromatic ammonium cations, can enhance hydrophobicity by preventing water molecules from penetrating and destroying the inorganic layers. Thus 2D perovskites usually demonstrate improved environmental stability against moisture. [8-10] Importantly, 2D perovskite crystals also showed unique optical properties such as deep blue emission and strong excitonic effect due to the strong quantum well effect. [11] Furthermore, targeting on the instability issue of hybrid perovskites under high-temperature and humid environments, scientists prompted all-inorganic perovskites (e.g., CsPbX 3) by replacing the organic component with inorganic ions. [12] Besides the rapid development of perovskite-based photovoltaics, [13-16] other perovskite-related devices including lightemitting diodes (LED), [17-20] laser, [21-23] transistors, [24] thermoelectric generators, [25] photodetectors for UV-NIR photons, [26-29] and various sensors for gas, chemical, and pressure have been widely studied. [30-33] Among all these potential applications, detectors and sensors became very active areas of research and even the third-largest application behind photovoltaics and LEDs (Figure 1). This trend could, again, be attributed to the favorable intrinsic properties of hybrid halide perovskites such as direct and tunable bandgaps with significant absorption coefficients, ultralong charge carrier lifetimes/diffusion lengths, high carrier mobilities, low charge carrier recombination, broad Optoelectronic devices based on perovskite materials have shown significant improvement due to the direct and tunable bandgaps, large absorption coefficients, broad absorption spectra, high carrier mobilities, and long carrier diffusion lengths. In addition to the excellent performance in solar cells, scientists have utilized per...

Novel triarylamine-based coordination-saturated aryl Pd(II) halide complexes ligated by PEt 3 , PCy 3 , and P(o-tol) 3 were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. SuzukiMiyaura coupling polymerization of 2-(7-halide-9,9-dioctylfluoren-2-yl)21,3,2-dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy 3 or P(o-tol) 3 exhibited catalytic activity and realized the catalysttransfer polycondensation at 75 C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt 3 did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P(o-tol) 3 can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst-transfer polymerization.

Dendrimeric Pt(II) complexes [(C(∧)N)Pt(dpm)] and [Pt(C(∧)N)2] (Hdpm = dipivaloylmethane, HC(∧)N = 1,2-diphenylbenzoimidazole and its derivatives containing the carbazole dendrons) have been synthesized and characterized systematically. All of the complexes display green emission in the range of 495-535 nm that originated from the 360-440 nm absorption bands, which are assigned to dπ(Pt)→π*(L) metal-to-ligand charge transfer (MLCT) mixed with intraligand π(L)→π*(L) transition. Solution photoluminescence quantum yield (φp 0.26-0.31) of the heteroleptic complexes [(C(∧)N)Pt(dpm)] obviously increases when compared with that of complex [(C(∧)N)Pt(acac)]. Organic light-emitting diode devices based on these Pt(II) complexes with a multilayer configuration were fabricated and gave desirable electroluminescent (EL) performances, such as non- or less red-shifted EL spectra, in comparison with the photoluminescence spectra and slow efficiency roll-off with increasing brightness or current density. Complex [(t-BuCzCzPBI)Pt(dpm)] (where t-BuCzCzPBI = 1-(4-(3,6-di-(3,6-di-t-butyl-carbazol-9-yl))carbazol-9-yl)phenyl-2-phenylbenzoimidazole) showed the best performance, with a maximum current efficiency of 29.31 cd/A and a maximum external quantum efficiency (EQE) of 9.04% among the fabricated devices. Likewise, for homoleptic [Pt(t-BuCzCzPBI)2] dendrimer, the powder φp (0.14) and maximum EQE (0.74%) improve by 7 and 7.4 times, respectively, as high as they do for nondendrimeric [Pt(1,2-diphenylbenzoimidazole)2] (0.02, 0.10%), although its efficiency is still lower than that of the heteroleptic counterpart due to the severely distorted square-planar geometry of the emitting core. These results reveal that large steric hindrance from ancillary ligand (dpm) or the homoleptic conformation can effectively inhibit intermolecular interaction for these dendrimeric Pt(II) complexes.

A di-(2-pyridylmethyl)phenylamine ((PyCH)NPh) supported Cu(ii)/O catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCH[double bond, length as m-dash]NPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCHNHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates. A cyclic catalytic mechanism was proposed including the base triggered C-H bond activation of the 2-pyridylmethyl group (PyCH-) and the intermolecular Cu-OOH α-hydrogen atom abstraction from the coordinated imine substrate (PyCH[double bond, length as m-dash]NPh).

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Poly(9,9-dioctylfluorene) (PFO) with M(n) values above 100,000 g mol(-1) in a toluene/water system and M(n) values up to 600,000 g mol(-1) in a THF/water system has been obtained by improved Suzuki polycondensation using a new kind of amphipathic palladium catalyst with self-phase-transfer features, which could overcome the disadvantage caused by the immiscible biphasic mixture and accelerate the transmetalation step.