Interdiscipline between optoelectronic materials and mechanical sensors: Recent advances of organic triboluminescent compounds and their applications in sensing

Poly(diarylfluorene) Deep-Blue Polymer Light-Emitting Diodes Based on Submicrometer-Scale Morphological Films Induced by Trace β-Conformation

“…Since the first polymer light-emitting diodes (PLEDs) were reported in the 1990s, , light-emitting conjugated polymers (LCPs) have attracted more attention for their easy structural modification, low-cost solution processing, and potential mechanical flexibility, which are extensively applied in information display and solid light, wearable devices, and bioelectronic equipments. − Precisely tuning the electronic structure and π–electron delocalization of LCPs via p–n (D–A) molecular engineering is a fundamental and universal strategy to optimize the photophysical properties and semiconducting behaviors toward optoelectronic applications. − In general, due to strong face-to-face electrostatic and π–π interactions of planar aromatic unit-containing conjugated chains, they can easily pack together and self-assemble into an ordered, oriented, and uniform aggregate under extremely concentrated states. − Therefore, as a bridge between chemical structures and optoelectronic devices, the film morphology is one of the key factors to govern the exciton and carrier behaviors and further improve the performance of optoelectronic devices. ,,− The micro- or nanostructures of LCPs can be divided into three types: amorphous, ordered aggregates, and semicrystalline structures. Here, the secondary chain conformation and tertiary phase transition can be tuned via physical methods to meet the various requirements of organic devices. − Therefore, in LCP films, synergistic effects of the surface and inner submicrometer-scale and tertiary condensed structures can radically control the properties of charge transport and neutral excited species. ,,,,− The formation of these interchain aggregates of LCPs always results in low-energy band gaps, causing long-wavelength emission, which is undesirable for deep-blue PLEDs. ,,− However, relatively ordered submicrometer-scale structures of the film are beneficial for enhancing charge transport and semiconducting properties, which ensure excellent device performance and high stability. ,,, In this regard, it is necessary to balance the chain hierarchical structure and photophysical processing of deep-blue LCPs toward fabricating efficient and stable deep-blue PLEDs.…”