Single‐emitting‐layer white organic light‐emitting diodes (SEL‐WOLEDs) have developed rapidly in recent years due to the outstanding advantages of high efficiency, simple device structure, low cost, less phase separation, and stable emission color. Nevertheless, the relatively complicated host‐dopant system is usually essential for most previous SEL‐WOLEDs and the development of simple non‐doped SEL‐WOLEDs lags behind. Hence the straightforward synthesis of single‐white‐emitting molecules for non‐doped SEL‐WOLEDs still remains a great challengeable task. In this article, we designed and synthesized two new pyrene‐based polyaromatic hydrocarbons (PAHs) and used them as emitting layer materials in the OLED devices. When the molecules change from the mono‐fused one to bis‐fused one, the emitting light changes from greenish to white color. Further study indicated that the bis‐fused molecule PyD with more twisted and extended backbone packed in neat Cmca space group in single‐crystal system compared with P21/n for PyS, which may be favorable to form excimers in the solid state and broaden the emission spectrum in the OLEDs. As a result, a solution‐processed non‐doped single‐white‐emitting‐molecule SEL‐WOLED with high performance (e. g., a high color rendering index of 66) is reported. The findings will be beneficial not only to further development of simple WOLEDs, but also to other related organic optoelectronic technology.

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Development of new n‐type one‐dimensional (1D) self‐assembly nanostructure and a clear understanding of the relationship between molecular structure and self‐assembly behavior are important prerequisites for further designing and optimizing organic optoelectronic nanodevice. In this article, a series of n‐type organic semiconductor materials based on pyrene imide were successfully synthesized through [4+2] cycloaddition reactions and their preliminary optical and electrochemical properties were studied. The simulated HOMO‐LUMO bandgaps via DFT tallied with the experimental data well. The self‐assembly of these materials showed needle or fiber‐like morphologies, indicating that different conjugation degree or alkyl group had significant influence on their self‐assembly behaviors. Furthermore, the single‐crystal packing for these molecules were analyzed and it was found out that the changes of conjugated backbone and functional group would affect certain crystal lattice parameter significantly, such as the intermolecular packing distance and crystal size etc, which would further result in different self‐assembly morphology.

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