Black phosphorus nanoribbons (PNRs) are ideal candidates for constructing electronic and optoelectronic devices owing to their unique structure and high bandgap tunability. However, the preparation of high‐quality narrow PNRs aligned along the same direction is very challenging. Here, a reformative mechanical exfoliation approach combining tape and polydimethylsiloxane (PDMS) exfoliations to fabricate high‐quality, narrow, and directed PNRs with smooth edges for the first time is developed. In this method, partially‐exfoliated PNRs are first formed on thick black phosphorus (BP) flakes via the tape exfoliation and further peeled off to obtain separated PNRs via the PDMS exfoliation. The prepared PNRs have widths from a dozen to hundreds of nanometers (down to 15 nm) and a mean length of 18 µm. It is found that the PNRs can align along a same direction and the length directions of directed PNRs are along the zigzag direction. The formation of PNRs is attributed to that the BP prefers to be unzipped along the zigzag direction and has an appropriate magnitude of interaction force with the PDMS substrate. The fabricated PNR/MoS2 heterojunction diode and PNR field‐effect transistor exhibit good device performance. This work provides a new pathway to achieve high‐quality, narrow, and directed PNRs for electronic and optoelectronic applications.

Narrow graphene nanoribbons (GNRs) and GNR/single-walled carbon nanotube (SWNT) intramolecular heterojunctions are ideal candidates to construct next-generation electronic and optoelectronic devices. However, the fabrication of high-quality long sub-5 nm wide GNRs and GNR/SWNT heterojunctions is a great challenge. Here, we report a method to produce high-quality sub-5 nm wide GNRs with smooth edges and GNR/SWNT intramolecular heterostructures via palladium-catalyzed full and partial unzipping of SWNTs, respectively. The resulting GNRs could be as narrow as 2.2 nm and had an average length of over 1 μm. By adjusting the unzipping time and the deposited positions of palladium nanoparticles, controlled multiple GNR/SWNT heterostructures were also fabricated on an individual parent SWNT. A GNR field-effect transistor (FET) constructed by a 3.1 nm wide GNR could simultaneously achieve a high on/off current ratio of 1.1 × 104 and a large mobility of 598 cm2 V–1 s–1. The photovoltaic device based on a single GNR (2.4 nm in width)/SWNT (0.8 nm in diameter) heterojunction exhibited a large open-circuit voltage (V oc) of 0.52 V and a high external power conversion efficiency (η) of 4.7% under the 1550 nm wavelength illumination of 931 mW cm–2. Our method provides a pathway to controllably prepare high-quality sub-5 nm GNRs and GNR/SWNT heterojunctions for fundamental studies and practical applications in the electronic and optoelectronic fields.

No abstract

The performance of diodes, which are the basic building blocks in integrated circuits, highly depends on the materials used. Black phosphorus (BP) and carbon nanomaterials with unique structures and excellent...

The preparation of high-quality narrow black phosphorus nanoribbons (PNRs) aligned along the same direction is very challenging. In article number 2207538, Changxin Chen and co-workers develop a reformative mechanical exfoliation approach combining tape and polydimethylsiloxane (PDMS) exfoliations to fabricate high-quality, narrow and directed PNRs with smooth edges. The prepared PNRs have widths from a dozen to hundreds of nanometers and can align along a same direction with their length directions along the zigzag direction.