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A high-triplet-energy host polymer consisting of 9-(4-(bis(9-(2-ethylhexyl)-9H-carbazol-3-yl)methyl)phenyl)-9H-carbazole and tetraphenylsilane units was designed and synthesized. The triplet energy (2.67 eV) is one of the highest values reported for conjugated polymer hosts. Suitable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of −5.61 and −2.24 eV, respectively, were also observed. Blue phosphorescent polymers were obtained by introducing bis[2-(4,6-difluorophenyl)pyridinato-N,C 2′]iridium(III) picolinate (FIrpic) into the host polymer while white phosphorescent polymers were synthesized by introducing red emissive bis[2-phenylquinoline-N,C 2′]iridium(III) picolinate ((Phq)2Irpic) into the blue phosphorescent one. Polymer light-emitting devices with the configuration ITO/PEDOT:PSS/PVK/EML/TSPO1/LiF/Al [ITO, indium tin oxide; PEDOT, poly(3,4-ethylenedioxythiophene); PSS, poly(styrenesulfonic acid); PVK, poly(N-vinylcarbazole); EML, the emitting layer was composed of polymer or polymer and 1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7) in a doping ratio of 2:1); TSPO1, diphenylphosphine oxide-4-(triphenylsilyl)pheny] were subsequently fabricated. Efficient energy transfer from the host polymer to the blue and red iridium(III) complexes was observed owing to the high triplet energy of the host. One of the fabricated blue phosphorescent devices had a maximum luminous efficiency of 3.57 cd/A.

High-defect density in thermodynamics driven directed self-assembly (DSA) flows has been a major cause of concern for a while and several questions have been raised about the relevance of DSA in high-volume manufacturing. The major questions raised in this regard are: (1) What is the intrinsic level of DSA-induced defects? (2) Can we isolate the DSA-induced defects from the other processes-induced defects? (3) How much do the DSA materials contribute to the final defectivity and can this be controlled? (4) How can we understand the root causes of the DSA-induced defects and their kinetics of annihilation? (5) Can we have block copolymer anneal durations that are compatible with standard CMOS fabrication techniques (in the range of minutes) with low-defect levels? We address these important questions and identify the issues and the level of control needed to achieve a stable DSA defect performance.

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Transparent and conducting flexible electrodes have been successfully developed over the last few decades due to their potential applications in optoelectronics. However, recent developments in smart electronics, such as a direct human-machine interface, health-monitoring devices, motion-tracking sensors, and artificially electronic skin also require materials with multifunctional properties such as transparency, flexibility and good portability. In such devices, there remains room to develop transparent and flexible devices such as pressure sensors or temperature sensors. Herein, we demonstrate a fully transparent and flexible bimodal sensor using indium tin oxide (ITO), which is embedded in a plastic substrate. For the proposed pressure sensor, the embedded ITO is detached from its Mayan-pyramid-structured silicon mold by an environmentally friendly method which utilizes water-soluble sacrificial layers. The Mayan-pyramid-based pressure sensor is capable of six different pressure sensations with excellent sensitivity in the range of 100 Pa-10 kPa, high endurance of 105 cycles, and good pulse detection and tactile sensing data processing capabilities through machine learning (ML) algorithms for different surface textures. A 5 × 5-pixel pressure-temperature-based bimodal sensor array with a zigzag-shaped ITO temperature sensor on top of it is also demonstrated without a noticeable interface effect. This work demonstrates the potential to develop transparent bimodal sensors that can be employed for electronic skin (E-skin) applications.