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Nonbenzenoid polycyclic arenes have attracted great attention because of their unique topological structures and appealing properties; however, they are generally considered as poor luminescent materials due to the ring puckering behavior of the nonhexagons. Acepleiadylene (APD), a nonbenzenoid isomer of pyrene, has been demonstrated as an excellent building block for optoelectronic applications, but its poor photoluminescence quantum yield (PLQY) has hampered its application in luminescent materials. Considering that the ring puckering character can be suppressed by increasing the rigidity of the nonhexagon rings, herein, we propose a novel strategy for enhancing the aromaticity of the nonhexagons to improve the PLQYs of APD derivatives. Electron-withdrawing cyano groups are introduced on the five-membered ring of APD to enhance the charge-separated character and thus the aromaticity of the nonhexagons, endowing the cyano-substituted APDs (CNAPD and 2CNAPD) with better rigidity. Therefore, the cyano substitution successfully suppresses the nonradiative energy dissipation caused by the ring puckering, improving the PLQY from 2.4% for APD to 14% for CNAPD, and to 63% for 2CNAPD. In addition, the enhanced rigidity also suppresses the vibration sideband of the photoluminescence spectra, leading to an ultra-narrowband emission from 2CNAPD with a full-width at half-maximum (FWHM) of 13 nm (47 meV), which is a new record in organic molecules. These results demonstrate that APD derivatives have great potential in highly efficient luminescent materials with high color purity via the aromaticity regulation strategy, which provides a novel concept for designing nonbenzenoid luminescent materials.

Bottom-up synthesized graphene nanoribbons (GNRs) are increasingly attracting interest due to their atomically controlled structure and customizable physical properties. In recent years, a range of GNR-based field-effect transistors (FETs) has been fabricated, with several demonstrating quantum-dot (QD) behavior at cryogenic temperatures. However, understanding the relationship between the cryogenic charge-transport characteristics and the number of the GNRs in the device is challenging, as the length and location of the GNRs in the junction are not precisely controlled. Here, we present a methodology based on a dual-gate FET that allows us to identify different scenarios, such as single GNRs, double or multiple GNRs in parallel, and a single GNR interacting with charge traps. Our dual-gate FET architecture therefore offers a quantitative approach for comprehending charge transport in atomically precise GNRs.