偏置电场对聚对苯乙烯激发态弛豫特性的影响

为探讨洞悉电场对有机发光二极管电致荧光量子效率的影响，通过激发-探测超快光谱技术研究了激子在电场下的瞬态行为.与单重态激子相应的激发态在230 μJ/cm2激发强度下，显示了快慢两个弛豫过程. 快慢组分的权重因子及快组分弛豫时间常数是电场相关的， 在6.4×10⁵ V/cm的电场下，与无偏置电场相比，激子的快组分弛豫时间加速，快组分的权重因子由22%增加为72%，约50%的初始激子又通过电场而离解. 慢组分是电场无关的，其弛豫时间常数为890 ps. 实验结果还揭示了由激发光所产生的长程声学声子，其声速为17 /ps. 关键词： 聚对苯乙烯 超快光谱 激子 有机发光二极管

Effect of the electric field on the decay of excited states in poly-phenylenevinylene

To gain an insight into the effect of electric field on the electro-luminescence of organic light emission diode,the ultrafast pump-probe spectroscopy is used to investigate the transient phenomena of the excitons induced by the electric field.Under the excitation density of 230μJ/cm~2,the decay of the singlet excitons shows a fast and a slow component.The amplitude factor and the relaxation time of fast component are field-dependent.Compared with the zero biascase,the relaxation time of the fast component becomes faster at a bias of 6.4×10~5 V/cm,its amplitude factor is increased from 22%to 72%,about 50%initial excitons are dissociated by the electric field.The slow component is field-independent,its relaxation time-constant is about 890 ps.The longitudinal acoustic phonons with sound velocity of 17(A)/ps generated by excitation pulse are observed.