Zhang Ting, Xu Zheng, Chen Xiao-hong, Shen Hong, Liu Shu-man
Institute of Optoelectronics, Laboratory of Materials for Information Storage and Display, Northern Jiaotong University, Beijing 100044, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2002 Dec;22(6):891-4.
Two devices structures of ITO/PVK: Rubrene/Al and ITO/Alq3:MN-PPV/Al were developed. Their characters of photoluminescence and electroluminscence were studied. The result showed that there were great difference between the photoluminescence and electroluminscence at a doping ratio of 2 wt% in ITO/PVK: Rubrene/Al. It is concluded that energy transfer in these dye-doped devices occurred by Förster energy transfer processes. And the trap effect of electrons of Rubrene on holes of PVK resulted in different combination probability of PVK excitation in photoluminescence and electroluminescence. At the same time, the two EL devices were color-tunable when the bias voltage was increased. The mechanisms which cause color variation are different. In the first device, it indicates that the energy transfer process from PVK to Rubrene is not complete. The combination probability of PVK excitation which does not contribute to the emission of Rubrene is increased when the bias voltage increases. But in the second device, there are many micro-interfaces due to the phase-separation just like the interface in a double layer device. The tunneling interface barriers of carriers is the main cause of color variation in the second device.
制备了ITO/PVK:Rubrene/Al和ITO/Alq3:MN-PPV/Al两种器件结构。研究了它们的光致发光和电致发光特性。结果表明，在ITO/PVK:Rubrene/Al中，掺杂比例为2 wt%时，光致发光和电致发光存在很大差异。得出结论：这些染料掺杂器件中的能量转移是通过Förster能量转移过程发生的。并且Rubrene的电子对PVK的空穴的陷阱效应导致了光致发光和电致发光中PVK激发的不同复合概率。同时，当偏置电压增加时，两种电致发光器件均可实现颜色可调。导致颜色变化的机制不同。在第一种器件中，这表明从PVK到Rubrene的能量转移过程不完全。当偏置电压增加时，对Rubrene发射没有贡献的PVK激发的复合概率增加。但在第二种器件中，由于相分离存在许多微界面，就像双层器件中的界面一样。载流子的隧穿界面势垒是第二种器件中颜色变化的主要原因。
