Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

Aggregation-Induced Emission: Together We Shine, United We Soar!

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure–property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).

Aggregation-induced emission

Aggregation-induced emission: phenomenon, mechanism and applications.

A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

"United we stand, divided we fall."--Aesop. Aggregation-induced emission (AIE) refers to a photophysical phenomenon shown by a group of luminogenic materials that are non-emissive when they are dissolved in good solvents as molecules but become highly luminescent when they are clustered in poor solvents or solid state as aggregates. In this Review we summarize the recent progresses made in the area of AIE research. We conduct mechanistic analyses of the AIE processes, unify the restriction of intramolecular motions (RIM) as the main cause for the AIE effects, and derive RIM-based molecular engineering strategies for the design of new AIE luminogens (AIEgens). Typical examples of the newly developed AIEgens and their high-tech applications as optoelectronic materials, chemical sensors and biomedical probes are presented and discussed.

Aggregation-Induced Emission: The Whole Is More Brilliant than the Parts

I. Semiconducting Polymers as Materials for “Plastic” Photonics Devices Solid-state photonic devices are a class of devices in which the quantum of light, the photon, plays a role. Because the interband optical transition (absorption and/or emission) is involved in photonic phenomena and because photon energies from near-infrared to near-ultraviolet are of interest, the relevant materials are semiconductors with band gaps in the range from 1 to 3 eV. Typical inorganic semiconductors used for photonic devices are Si, Ge, and Group III-V and Group II-VI alloys.1 Conjugated polymers are a novel class of semiconductors that combine the optical and electronic properties of semiconductors with the processing advantages and mechanical properties of polymers. Important examples of polymers within this class include poly(p-phenylenevinylene) (PPV), poly(p-phenylene) (PPP), and polyfluorene (PF) derivatives whose molecular structures are shown in Figure 1. The relative simplicity with which high photoluminescence (PL) efficiency polymers of different colors can be achieved is in stark contrast to inorganic semiconductors, where, for example, bright blue light emitting diodes (LEDs) were not available until recently because of the difficulties in growing InGaN films.2 Most of the photonic phenomena known in conventional inorganic semiconductors have been observed in these semiconducting polymers. The dream of using such materials in high-performance “plastic” photonic devices is rapidly becoming reality: high-performance photonic devices fabricated from conjugated polymers have been demonstrated, including diodes,3 light-emitting diodes,4 photodiodes,5 field-effect transistors,6 polymer grid triodes,7 light-emitting electrochemical cells,8 and optocouplers,9 i.e., all the categories that characterize the field of photonic devices. These polymer-based devices have reached performance levels comparable to or even better than those of their inorganic counterparts. For a recent review of progress in plastic photonic devices fabricated with semiconducting polymers, see ref 10.

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New Developments in the Photonic Applications of Conjugated Polymers

We report white light emission from InGaN/conjugated polymer hybrid light-emitting diodes (LEDs). White light sources (or sources with various colors) are achieved by combining the photoluminescence (PL) from semiconducting (conjugated) polymers with the emission from high efficiency InGaN based LEDs; the InGaN based LED provides the blue component and, simultaneously, serves as the short wavelength pump source for exciting the PL of the polymer film(s).

White light from InGaN/conjugated polymer hybrid light-emitting diodes

Gain narrowing and lasing from a soluble, highly photoluminescent conjugated polymer, poly(2-butyl, 5-(2′-ethyl-hexyl)-1,4-phenylene vinylene) (BuEH-PPV), are compared using two resonant structures: planar waveguides and microcavities. The gain narrowing and lasing thresholds are comparable, 0.05–0.1 μJ (10 ns pulse focused to ∼1.5 mm). Gain narrowing is not observed in films on indium tin oxide (ITO) unless a cladding layer is placed between the BuEH-PPV and ITO. Single-mode microcavity lasers are obtained when a cavity resonance occurs at the wavelength where the gain of the polymer is maximum.

http://www.chem.ucla.edu/dept/Faculty/schwartz/schwartz_pubs/APL_70_3191_1997.pdf

“Plastic” lasers: Comparison of gain narrowing with a soluble semiconducting polymer in waveguides and microcavities

Hybrid inorganic light emitting device/luminescent polymer light-emitting sources for efficient and cost effective white lighting and for full-color applications and their manufacture are disclosed. The hybrid light sources include an inorganic light-emitting source such as a p-n junction diode-containing device capable of emitting a first emitted output of light and a photoluminescent polymer element positioned in the first emitted output of light, the polymer being selected to be capable of being pumped by a first portion of the first emitted output of light and when so pumped of emitting a second emitted output of light which is emitted from the device with that portion of the first emitted output remaining beyond the first portion.

Hybrid light-emitting sources for efficient and cost effective white lighting and for full-color applications

Solid state lasers based upon conjugated polymers are disclosed A conjugated polymer useful in the practice of this invention is a conjugated polymer which has a ground state and an excited state and which, in the form of a nondiluted thin film, meets the criteria of; i having a strong absorption in the ground state with an absorption coefficient of at least about 104 cm-1 and an absorption depth not greater than about 1 μm, ii having an efficient luminescence emission from the excited state; this emission being shifted to lower energy relative to the ground state absorption, and iii providing stimulated emission which is not overwhelmed by photoinduced absorption, such that the thin film exhibits gain narrowing and amplified spontaneous emission These conjugated polymers have gain lengths in the micron or even sub-micron regime and therefore exhibit laser action with low pumping threshold as thin solid films with thicknesses in the micron or even sub-micron regime

Fumitomo Hide

Papers

New Developments in the Photonic Applications of Conjugated Polymers

White light from InGaN/conjugated polymer hybrid light-emitting diodes

“Plastic” lasers: Comparison of gain narrowing with a soluble semiconducting polymer in waveguides and microcavities

Hybrid light-emitting sources for efficient and cost effective white lighting and for full-color applications

Conjugated polymers as materials for solid state laser