耦合结构有机微腔的光致发光特性

Optical Properties of Organic Film in a Coupled Microcavity

耦合光学微腔(Coupled optical microcavity,CMC)是一种特殊结构的微腔,在耦合微腔中,两个独立的微腔相邻耦合在一起。通常一个腔是无源的,另一个腔是有源的。首次研究了有机材料在耦合微腔中的自发发射特性。实验采用的有机发光材料为八羟基喹啉铝Tris(8-quinolinolato)aluminium(Alq3),器件的结构为Glass/DBRA/Filler/DBRB/Alq3/DBRC。底部腔是无源的,组成为DBRA/Filler/DBRB。顶部腔是有源的,由DBRB/Alq3/DBRC构成。其中反射镜DBRA、DBRB、DBRC以及填充层(Filler)均由光学介质材料构成。通过结构设计使两个腔的谐振波长均位于530nm。耦合微腔器件与单层Alq3薄膜相比较,Alq3薄膜的光致发光光谱是峰值位于511nm的宽谱带,而在耦合微腔器件中观察到的是具有两个腔模式,峰值波长分别位于518,553nm的增强并窄化的光谱。这是由于两个腔的光场耦合引起了腔模式分裂。结果表明耦合微腔能极大地改变有机材料的自发发射特性,可以用来提高器件的发光效率。

Great interest has been shown in the physics and applications of Fabry-Perot optical microcavity.The spontaneous emission properties of a light emitting material, such as spectrum shape and emission distribution, can be tailored in optical microcavities that have dimensions comparable to an optical wavelength. Up to now, many applications with one-dimensional microcavity structures have been reported, such as resonant light-emitting diodes, vertical-cavity surface emitting lasers and microcavity organic light-emitting diodes （OLEDs）. Microcavity OLEDs have shown abilities to reduce the emission bandwidth, improve the color purity, and increase luminous efficiency as compared to those of normal OLEDs. Coupled optical microcavity （ CMC ） is a structure consists of two or more planar Fabry-Perot microcavities that are coupled to each other. Lately, CMCs have been investigated to show very different emission characteristics compared with a single Fabry-Perot microcavity, which presents many potential applications, for instance highly selective wavelength filters, bistable devices, a range of optical and electro-optic switches. In this paper, spontaneous emission properties of a coupled optical microcavity based on an organic light emitting material have been studied under optical excitation for the first time. The structure of the CMC is glass/DBRA/filler/DBRB/tris （8-quinolinolato） aluminium （ Alq3 ）/DBRc. The bottom cavity and top cavity were formed by DBRA/filler/DBRB and DBRB/Alq3/DBRc, respectively. Compared with a broadband spectrum of Alq3 film centered at 511 nm, spectral narrowing and intensity enhancement at the two cavity modes 518,553 nm was observed in CMC. The results indicate that CMC structure can strongly modifies the spontaneous emission properties of organic material. The CMC structure may be used as an efficient approach of improving luminous efficiency and can be used to develop potential new type organic photoelectric devices.