All organic transport materials (TMs) based QLEDs: Revisiting molecular electron TMs with mapping hole TMs via cross-linking strategy

Nondestructive Direct Patterning of Both Hole Transport and Emissive Layers for Pixelated Quantum-Dot Light-Emitting Diodes

“…This cross-linking process was much more robust when comparing the fact that TFB:X1 and TFB:X2−X5 needed a weight ratio of 5:1 and 10:1, respectively. 26,39 Additionally, decreasing the weight ratio of X8/X9 to 50:1 can still maintain over 90% of the original absorbance after rinsing. These findings demonstrate the high solvent resistance of the two developed tridentate cross-linkers.…”

“…By systematically optimizing the weight ratios of TFB:X8/X9, it was found that the tridentate carbene precursors, X8 and X9, both can provide cross-linked films with >95% solvent resistance even at an extremely low cross-linker weight ratio of 30:1 (TFB:X8/X9). This cross-linking process was much more robust when comparing the fact that TFB:X1 and TFB:X2–X5 needed a weight ratio of 5:1 and 10:1, respectively. , Additionally, decreasing the weight ratio of X8/X9 to 50:1 can still maintain over 90% of the original absorbance after rinsing. These findings demonstrate the high solvent resistance of the two developed tridentate cross-linkers.…”

“…35−38 Previously, we reported that a series of bis-diazo compounds (X1−X5) can effectively cross-link with polymeric poly[(9,9dioctylfluorenyl-2,7-diyl)-alt(4,4′(N-(4-butylphenyl)))] (TFB) by a photothermal synergistic curing process. 26,39 However, these bidentate cross-linkers need high doping ratios to guarantee nearly full solvent resistance of the resulted HTL, requiring large doses of UV irradiation and thus without affording patternability.…”

“…Despite these advances, the direct patterning of the polymeric HTL in QLEDs has yet to be shown. Carbene cross-linkers are of great interest due to their high activity and wide applications in optoelectronic devices. − Previously, we reported that a series of bis-diazo compounds (X1–X5) can effectively cross-link with polymeric poly­[(9,9-dioctylfluorenyl-2,7-diyl)-alt­(4,4′( N -(4-butylphenyl)))] (TFB) by a photothermal synergistic curing process. , However, these bidentate cross-linkers need high doping ratios to guarantee nearly full solvent resistance of the resulted HTL, requiring large doses of UV irradiation and thus without affording patternability.…”

Improving the Performance of Quantum Dot Light-Emitting Diodes by the Enrichment of a Fluorinated Component on Top of a Hole Transport Layer

“…The TFB is one of the most widely used HTLs in QLEDs due to the high hole carrier mobility; however, its highest occupied molecular orbital (HOMO) is about −5.3 ± 0.1 eV, which is not suitable for the QD with deep energy bands, especially the green and blue QDs . Various chemical approaches were reported to modify the molecular structure of TFB to lower the HOMO toward better energy-level alignments. , For example, a TFB derivative with 2-cyanopropan-2-yl was developed with high conductivity and stabilized HOMO for the QLED applications . TF-DCF3 was also developed with two electron-withdrawing trifluoromethyl groups attached to the triphenylamine units, leading to 0.22 and 0.07 eV downshifts of the E HOMO and the lowest unoccupied molecular orbital energy level ( E LUMO ), respectively, agreeing with the previous report .…”