液晶發光高分子於導電配向層上的自身排列現象

Abstract

近年來偏極化高分子發光二極體引起愈來愈多的研究，因為其具有很大的潛力能取代傳統液晶顯示器中的背光模組與線偏極板。為了製作出高偏極化高分子發光二極體，在此論文中，我們是針對各種會影響高分子發光材料排列現象的因素，像是發光高分子濃度、塗佈轉速、溶劑、退火時間以及退火溫度等等，在不同種類螢光高分子發光材料與配向膜材料上，作一系列詳盡的探討與分析。我們發現當螢光高分子濃度低時，其高分子較能有序的排列。而在塗佈轉速上，則隨著螢光高分子的濃度有最佳化的現象。在溶劑方面，因為螢光高分子在不同溶劑中的分子捲曲型態不同，進而會影響排列的情形。另外，在退火時間和退火溫度方面，在低退火溫度時，增加退火時間能有效提升分子排列性。但在高退火溫度下，退火時間的長短則幾乎是與分子排列情形無關。 接著，我們成功的製作出嶄新的導電配向膜。是利用PVA混合PEDOT/PSS Al 4071當配向層，做出能大幅提升偏極化的高分子發光二極體。 針對2/6型螢光高分子而言，採用機械研磨方式的純PEDOT/PSS Al4071配向層，其偏極化率無法有出色的表現。因此，我們改採用了所提出的配向膜，PVA水溶性材料混於導電高分子PEDOT中作為配向層，其螢光光譜偏極化率RPL及其積分比分別為7.11、6.58，相較於純PEDOT可提升7倍之多；而偏極化率REL可高達16.2 (在波長為548nm)，其積分值也可達16.1，相較於純Al 4071導電配向膜提升了16倍之多。

Recently, polarized polymer light-emitting diodes (PLEDs) have been studied extensively because of their great potential to replace the backlight module and the linear polarizer of thin-film transistor liquid crystal displays (TFT-LCDs). In order to fabricate highly polarized PLEDs, in this thesis, we firstly focus on the analysis of several factors which affect the arrangement of polyfluorenes, such as the concentration of solutions, spin rates, annealing time, and annealing temperature. It is found that polyfluorenes align more ordered while the concentration of polymer solution is lower. The spin rates should be optimized to achieve the best alignment of polymer chains while using different concentration of solutions. On the other hand, the solvent effect should be considered since it will affect the morphology of polyfluorenes. Moreover, at low annealing temperature, the alignment of polymers will be improved apparently by increasing the annealing time. However, it becomes almost independent at higher annealing temperature. Then, highly polarized PLEDs adopting a novel conducting alignment layer, consisting of PEDOT:PSS and PVA, have been successfully accomplished. For PF2/6, a high dichroic ratio can not be obtained while using conventional mechanical-rubbing method and neat PEDOT:PSS (Al 4071) as the alignment layer. After blending PVA with PEDOT:PSS as alignment layer, the maximum dichroic ratio and its integral value in visible region of photoluminescence are 7.11 and 6.58, respectively. In addition, the maximum dichroic ratio and its integral value of electroluminescence (at 548 nm) are 16.2 and 16.1, respectively. They are seven and sixteen times larger than those while using neat PEDOT:PSS as the alignment layer, respectively.