A simple three-layer interfacial-type yellow emission exciplex device with an external quantum efficiency as high as 7.7% has been successfully achieved by combining conformation compatible C3-symmetric hole-transporting TCTA and electron-transporting 3P-T2T. The excellent and balanced charge-transporting properties of TCTA and 3P-T2T and the large energy-levels offset (0.8 eV) of TCTA/3P-T2T interface play important roles for the efficient exciplexes formation, which are effectively confined around the interfacial region due to the high triplet energies (2.85 eV) of TCTA and 3P-T2T. The high-performance OLED was believed to be from the effective harvest of exciplex triplet excitons via reverse intersystem crossing process.

A unique "clean-lifting transfer" (CLT) technique that applies a controllable electrostatic force to transfer large-area and high-quality CVD-grown graphene onto various rigid or flexible substrates is reported. The CLT technique without using any organic support or adhesives can produce residual-free graphene films with large-area processability, and has great potential for future industrial production of graphene-based electronics or optoelectronics.

We report a homoleptic Au-Cu alkynyl cluster that represents an unexplored class of luminescent materials with stimuli-responsive photophysical properties. The bimetallic complex formulated as [Au(2)Cu(2)(C(2)OHC(5)H(8))(4)](n) efficiently self-assembles from Au(SC(4)H(8))Cl, Cu(NCMe)(4)PF(6), and 1-ethynylcyclopentanol in the presence of NEt(3). This compound shows remarkably diverse polymorphism arising from the modulation of metallophilic interactions by organic solvents. Four crystalline forms, obtained from methanol (1a); ethanol, acetone, or choloroform (1b); toluene (1c); and diethyl ether or ethyl acetate (1d), demonstrate different photoluminescent characteristics. The solid-state quantum yields of phosphorescence (Φ) vary from 0.1% (1a) to 25% (1d), depending on the character of intermetallic bonding. The structures of 1b-d were determined by single-crystal X-ray diffraction. The ethanol (1b, Φ = 2%) and toluene (1c, Φ = 10%) solvates of [Au(2)Cu(2)(C(2)OHC(5)H(8))(4)](n) adopt octanuclear isomeric structures (n = 2), while 1d (Φ = 25%) is a solvent-free chain polymer built from two types of Au(4)Cu(4) units. Electronic structure calculations show that the dramatic enhancement of the emission intensity is correlated with the increasing role of metal-metal bonding. The latter makes the emission progressively more metal-centered in the order 1b < 1c < 1d. The metallophilic contacts in 1a-d show high sensitivity to the vapors of certain solvents, which effectively induce unusual solid-state isomerization and switching of the absorption and luminescence properties via non-covalent interactions. The reported polymorphic material is the first example of a gold(I) alkynyl compound demonstrating vapochromic behavior.

Optical absorption, photoluminescence and Raman scattering of lead-halide based inorganic-organic perovskite semiconductors were measured under quasi-hydrostatic pressure at room temperature. For the 3D perovskite semiconductor, (CH 3 NH 3 )PbBr 3 , the free exciton photoluminescence band exhibits redshifts with pressure, and jumps to a higher energy by 0.07 eV at 0.8 GPa, which is associated with a phase transition from a cubic to an orthorhombic structure confirmed by Raman scattering. Above the phase transition pressure, the exciton band shows blue-shifts with further increasing pressure, and eventually disappears above 4.7 GPa. The results are compared with those for the 2D perovskite semiconductor, (C 4 H 9 NH 3 ) 2 PbI 4 . First principles pseudopotential calculations were performed to investigate changes in octahedral distortion and electronic band structures with pressure. The calculations have explained the origins of the intriguing changes in the electronic states with pressure in view of bonding characters between atomic orbitals in octahedra.

We have designed and synthesized a series of Au(I) complexes bearing either an alkynyl−(phenylene) n −diphosphine (A-0−A-3) or a (phenylene) n −diphosphine (B-1−B-5) bridge, among which the effective distance between Au(I) and the center of the emitting ππ* chromophore can be fine-tuned via the insertion of various numbers of phenylene spacers. We then demonstrated for the first time in a systematic manner the decrease of rate constant for S 1 → T 1 intersystem crossing (ISC) k isc as the increase of the effective distance. The results also unambiguously showed that the phosphorescence could be harvested via higher S 0 → S n (n > 1) electronic excitation, followed by fast S n → T m ISC and then the population at T 1 state, bypassing the relatively slow S 1 → T 1 ISC. The results unify a recent report on higher excited-state relaxation dynamics for the late transition metal complexes (J. Am. Chem. Soc. 2012, 134, 7715−7724). The dual, far separated fluorescence and phosphorescence of the titled complexes make feasible the white light generation in a single molecule unit, as successfully demonstrated using complex B-3 as a dopant to fabricate organic light emitting diodes.