Ionic discotic liquid crystals are salts of discotic liquid crystals that may display lyotropic and thermotropic mesomorphism. Columnar structures of π‐π stacking ionic discotic liquid crystals function not only as anisotropic organic semiconductors, similar to their neutral analogues, but they may also efficiently conduct ions. This combination of electronic and ionic conduction is only one of several unique properties that these materials may display, but their systematic investigation has been limited because of their often complex synthesis, purification, and characterization. However, a comprehensive account of existing reports on ionic discotic liquid crystals is not straightforward, despite their relatively small number, because publications are scattered across different areas of research, such as liquid crystals, ionic liquids, and ionic self‐assembly. This review intends to provide a concise but comprehensive overview of the published work on ionic discotic liquid crystals and related compounds and is expected to stimulate further exploration. Highlighted in this review is the mesomorphism of ionic discotic liquid crystals and its dependence on structural changes, which is also the focus of most reported studies. Particular attention was given to the dependence of mesomorphism on the location and types of the charged groups as these are parameters unique to these compounds. Also described are electronic, optical, and other properties of these materials if reported.
A strategy for efficaciously regulating perovskite crystallinity is proposed by using a volatile solid glycolic acid (HOCH2COOH, GA) in an FA0.85MA0.15PbI3 (FA: HC(NH2)2; MA: CH3NH3) perovskite precursor solution that is different from the common additive approach. Accompanied with the first dimethyl sulfoxide sublimation process, the subsequent sublimation of GA before 150 °C in the FA0.85MA0.15PbI3 perovskite film can artfully regulate the perovskite crystallinity without any residual after annealing. The improved film formation upon GA modification induced by the strong interaction between GA and Pb2+ delivers a champion power conversion efficiency (PCE) as high as 21.32%. In order to investigate the role of volatility in perovskite solar cells (PSCs), nonvolatile thioglycolic acid (HSCH2COOH, TGA) with a similar structure to GA is utilized as an additive reference. Large perovskite grains are obtained by TGA modification but with obvious pinholes, which directly leads to an increased defect density accompanied by a decline in PCE. Encouragingly, the champion PCE achieved for GA‐based PSC device (21.32%) is almost 13% or 20% higher than those of the control device or TGA‐based device. In addition, GA‐modified PSCs exhibit the best stability in light‐, thermal‐, and humidity‐based tests due to the improved film formation.
Quinoxalino[2',3':9,10]phenanthro[4,5-abc]phenazine (QPP) dyes have been studied as electron acceptor materials, fluorophores, and building blocks for self-organizing organic semiconductors. Condensation of tetraketopyrene with electron-rich diamino-terphenylene and -triphenylene derivatives generates new donor-acceptor QPP derivatives that display columnar mesomorphism over wide ranges of temperature; are fluorescent in solution, liquid crystal, and solid phases; and have electron acceptor properties. Also reported are the synthesis and properties of the first diamino-(tetraalkoxy)triphenylene as a valuable new synthon.
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