Self-assembled monolayers featuring multi-chlorinated carbazole unit for improving hole extraction efficiency in organic photoelectronic device

Improved Thermally Activated Delayed Fluorescence-Based Electroluminescent Devices Using Vacuum-Processed Carbazole-Based Self-Assembled Monolayers

“…These transient PL results are consistent with the previous reports and also in agreement with the SSPL intensity variation . Relative enhancement of the PL can be a plausible explanation for the defect passivation at the HIL/α-NPD/EML interface . Solution-processable Me-4PACz as HIL also showed slight enhancement in the charge carrier lifetime in comparison to PEDOT:PSS (Figure S4b,c, Table S2), which is in good agreement with the PL intensity variation (Figure S4a).…”

“…31 Relative enhancement of the PL can be a plausible explanation for the defect passivation at the HIL/α-NPD/EML interface. 20 Solution-processable Me-4PACz as HIL also showed slight enhancement in the charge carrier lifetime in comparison to PEDOT:PSS (Figure S4b,c, Table S2), which is in good agreement with the PL intensity variation (Figure S4a). We note that evaporated Me-4PACz is best among three different HIL-based samples for optical studies.…”

“…This relative enhancement in SSPL and improved PL lifetime of the half OLED stack for evaporated Me-4PACz vs PEDOT:PSS is not well understood, as there are multiple layers and interfaces involved; however, such approaches are being reported in the literature to explain the origin of non-radiative channels in a device stack and near lossless interface. 20 This is still under investigation in our laboratory. Another explanation could be the improved charge carrier balance 33 in the OLED, which leads to improved EQE.…”

“…19,18 Recently, multi-chlorinated carbazole-based SAMs have been used in OLEDs, demonstrating highly improved device performance and leading to the introduction of PEDOT:PSS-free OLEDs. 20 The latest major breakthrough in this field occurred when Albrecht and coworkers developed a series of such materials that form an essentially lossless hole transport layer (HTL)/active layer interface. 21 Their key finding was the design of two promising SAMs derived from carbazole bodies 22 phosphonic acid (MeO-2PACz).…”

Modification of ITO with Composite Self-Assembled Monolayer Enables Hole Injection and Transport Layer-Free TADF-OLED with Preferable Performance

“…To our knowledge, the commonly used approaches to simplify the device structure include modifying poly­(3,4-ethylenedioxythiophene): poly­(styrene-sulfonate) (PEDOT: PSS), − doping indium tin oxide (ITO) anode, − and modifying ITO with self-assembled monolayer (SAM). − Among them, modifying PEDOT: PSS and doping ITO anode can only omit a hole injection layer (HIL) or hole transport layer (HTL), while modifying ITO with SAMs presents the potential to leave out both of them to simplify the device structure furthest. Huang et al prepared an HIL- and HTL-free OLED device for the first time with n -butylsiloxane as a self-assembled molecule for ITO .…”