fig2

Figure 2. A: Molecular structure and HOMO levels of the four π-conjugated OSMs, The figure is quoted with permission from Kim et al.^[36]; B: molecular structure, bandgaps and HOMO/LUMO levels of the three stilbene-derivatives, The figure is quoted with permission from Kim et al.^[37]; C: molecular structures of dPhiz-6, Biz-6, Naphiz-6, and Pheniz-6, The figure is quoted with permission from Kim et al.^[38]; D: molecular structures of the spiro-bifluorene derivatives, The figure is quoted with permission from Zhu et al.^[39]. HOMO: Highest occupied molecular orbital; OSMs: organic small molecules; LUMO: lowest unoccupied molecular orbital; dCNBT: 2,5-bis([2,2’-bithiophene]-5-yl)-1,4-benzenedicarbonitrile; PBT: 5,5”-(1,4-phenylene)bis[2,2’-bithiophene]; mBT: 5,5”-(2-methoxy-1,4-phenylene)bis[2,2’-bithiophene]; dmBT: 5,5”-(2,5-dimethoxy-1,4-phenylene)bis[2,2’-bithiophene]; CzS: (E)-4,4’-bis[9-(3,6-dimethoxy-9H-carbazolyl)]stilbene; CzCNS: 4-(3,6-dimethoxy-9H-carbazole-9-yl)-α-[4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]methylene-(αZ)-benzenacetonitrile; CzdCNS: 1,2-dicyano-trans-1,2-bis-4-(carbazoylyl)phenylethylene.