Graphene quantum dots (GQDs) have emerged as a promising type of functional material with distinguished properties. Although tremendous effort was devoted to the preparation of GQDs, their applications are still limited due to a lack of methods for processing GQDs from synthesis to patterning smoothly. Here, we demonstrate that aromatic molecules, e.g., anisole, can be directly converted into GQD-containing nanostructures by cryogenic electron-beam writing. Such an electronbeam irradiation product exhibits evenly red fluorescence emission under laser excitation at 473 nm, and its photoluminescence intensity can be easily tuned with the electron-beam exposure dose. Experimental characterizations on the chemical composition of the product reveal that anisole undergoes a carbonization and further graphitization process during e-beam irradiation. With conformal coating of anisole, our approach can create arbitrary fluorescent patterns on both planar and curved surfaces for concealing information or anticounterfeiting applications. This study provides a one-step method for production and patterning of GQDs, facilitating their applications in highly integrated and compact optoelectronic devices.
The evolution of writing systems illustrates the development of information storage. Here, a unique way is demonstrated using sprayed anisole as the ink and a focused electron‐beam as a pen to record messages on a cooled substrate. Such an electron‐beam writing approach controls the thickness of remained anisole on the substrate. Optical interference at the visible region occurs thereby, resulting directly in a color print. Using discrete dose distribution, an 11‐step structure with a height difference of sub‐10 nm accuracy is written. A quinary pattern with a total thickness of 180 nm and unit square size of 500 nm is also written, implying information density beyond 1013 bits per cm3 (10 Tbit cm–3). Painting at the nanoscale is also enabled by importing grayscale images. In addition, the substrate can be extended from planar to nonplanar or flexible objects, such as an aluminum tape or a silver wire. Combining the grayscale lithographic nature and conformal coating of the ink, this writing process has great potential to store information on any surface.
Organic–inorganic hybrid perovskites (OIHPs) with superior optoelectronic properties have emerged as revolutionary semiconductor materials for diverse applications. A fundamental understanding of the interplay between the microscopic molecular-level structure and the macroscopic optoelectronic properties is essential to boost device performance toward theoretical limits. Here, we reveal the critical role of CH3NH3 + (MA) in the regulation of the physicochemical and optoelectronic properties of a MAPbI3 film irradiated by an electron beam at 130 K. The order-to-disorder transformation of the MA cation not only leads to a notably enhanced photoluminescence emission but also results in the suppression of the orthorhombic phase down to 85 K. Taking advantage of the regulation of MA cation dynamics, we demonstrate a perovskite photodetector with 100% photocurrent enhancement and long-term stability exceeding one month. Our study provides a powerful tool for regulating the optoelectronic properties and stabilities of perovskites and highlights potential opportunities related to the organic cation in OIHPs.
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