High Brightness Fluorescent White Polymer Light-Emitting Diodes by Promoted Hole Injection via Reduced Barrier by Interfacial Dipole Imparted from Chlorinated Indium Tin Oxide to the Hole Injection Layer PEDOT:PSS

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• 作者：Hong-Ren Syue ; Miao-Ken Hung ; Yao-Tang Chang ; Ge-Wei Lin ; Yu-Hsuan Lee ; Show-An Chen
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 1, 2017
• 年：2017
• 卷：9
• 期：4
• 页码：3824-3830
• 全文大小：496K
• ISSN：1944-8252

文摘

We demonstrated that introducing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as a hole transport layer (HTL) on top of chlorinated indium tin oxide (Cl-ITO) anode can lead to a deeper highest occupied molecular orbital level of the HTL (promoting from 5.22 to 5.42 eV) due to the interfacial dipole imparted by the Cl-ITO, which allows barrier-free hole injection to the emitting layer with polyspirobifluorene doped with the yellow emitter rubrene and significantly prevents excitons quenching by residual chlorine radicals on the surface of Cl-ITO. By use of poly[9,9-bis(6′-(18-crown-6)methoxy)hexyl)fluorene] chelating to potassium ion (PFCn6:K⁺) as electron injection layer and air-stable high work function (E_Φ) metal aluminum as the cathode, the performance of fluorescent white polymer light-emitting diode (WPLED) achieves the high maximum brightness (B_max) of 61 523 cd/m² and maximum luminance efficiency (η_L, _max) of 10.3 cd/A. Replacing PFCn6:K⁺/Al cathode by CsF/Al, the B_max and η_L, _max are promoted to 87 615 cd/m² (the record value in WPLED) and 11.1 cd/A, respectively.