摘要
利用高真空有机分子束沉积系统 ,将两种有机材料 ,叔丁基联苯基呃二唑 (PBD)和 8 羟基喹啉铝(Alq) ,以交替沉积的方式形成一种周期性多异质结结构。从这种结构的能带图上看 ,类似于无机半导体中的Ⅰ型量子阱结构 ,我们称之为有机量子阱结构。这种结构的光致发光 (PL)谱线和Alq薄膜的PL谱线相比 ,峰值向高能量方向偏移了 2 0nm ,峰值半高宽窄化了 2 5nm ,并对其结果进行了分析。
Periodic multilayer structures fabricated by alternate deposition two different organic materials are recognized as offering unique electrical and optical functions promising for high performance and new functionality devices. Considering the application of organic multilayer structures to various optical devices including highly efficient EL diodes and lasers, it seems desirable to explore material systems with the type Ⅰquantum well structure which has been one of the basic structure of semiconductor optical devices. Three periods multilayer structure was fabricated, in which tris(8 hydroxyquinoline) Alq and 2 (4 biphenylyl) 5 (4 tert butylphenyl) 1,3,4 oxadiazole were alternate deposited. The structure of the specimen was: PBD/Alq/ PBD/Alq/ PBD/Alq/PBD, in which the thickness of Alq was 3nm and PBD was 5nm, respectively. From the configuration and the energy band diagrams, the structure of the specimen was like inorganic quantum well structure, so conveniently, it was called organic quantum well structure in this paper, where PBD act as barrier potential and Alq as potential well. The photoluminescence (PL) spectrum of PBD are largely overlapped with the absorption spectrum of Alq, suggesting the possibility of resonance energy transfer or Frster transfer from PBD to Alq. The PL spectrum of the quantum well structure shows only peak at 508nm, which is Alq luminescence. And in the photoluminescence excitation (PLE) spectrum detecting Alq, the peak at 330nm is most dominated, which corresponding the absorption of PBD. So, the PL and PLE spectrum of the specimen prove that the period multilayer structure could possess carrier confinement type Ⅰ energy lineup. Compared the PL spectrum of the specimen with that of the single layer of Alq (20nm), the emission peak is shifted to higher energy by 20nm and the full width at half maximum (FWHM) is narrowed by 25nm. The phenomena were contributed to the confinement effect of the quantum well structure. Being confined energetically in the narrow potential well, the possibility of the carrier possessing the higher energy states is enhanced and the diffusion of Alq exitons is suppressed, which induce the increase of the higher energy component and decrease of the lower energy component of the PL spectrum. So the PL spectrum is blue shifted and narrowed considerably.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2002年第3期265-268,共4页
Chinese Journal of Luminescence
基金
国家自然科学基金资助项目 (5 9973 0 0 7
60 0 770 14 )
