半晶性有机半导体薄膜形态结构及对有机发光器件老化的影响

以NPB（N,N’-二苯基-N,N’-二（1-萘基）-1,1’-联苯-4,4’-二胺）为例,简要综述了本课题组近年来在发光有机半导体薄膜形态结构方面的研究进展．通过差热分析、偏光显微镜、透射电子显微镜、电子衍射、原子力显微镜表征,确认NPB是一类本征半晶性材料．一般的OLED器件采用的是非晶的NPB薄膜．基于等温结晶和表面诱导结晶实验确认,OLED器件可能存在两种热力学老化机制．对于采用非晶衬底的OLED器件,当NPB薄膜厚度小于临界厚度时器件可以稳定工作;对于采用多晶缓冲层衬底的OLED器件,由于表面诱导NPB结晶不存在临界厚度限制,器件容易结晶老化．

Morphology of thin-film of semi-crystalline organic semiconductors and influences on lifetime of OLED devices

Recent approaches on thin-film morphology of semi-crystalline organic light-emitting semiconductors done in our group are briefly reviewed. It has been confirmed that NPB is a semi-crystalline materials intrinsically. Thin-films used in OLED devices are normally in non-equilibrium glass state. Two types of device-decay mechanism using the amorphous thin-films are proposed based on thermal crystallization and crystalline surface induced crystallization. For the device using amorphous substrate, it is possible to obtain stable device when the thickness of NPB thin-films is less than a critical thickness. For the device using crystalline substrate, it is easy to crystallized without limitation of thin-film thickness.