Ultra-Small 2D PbS Nanoplatelets: Liquid-Phase Exfoliation and Emerging Applications for Photo-Electrochemical Photodetectors

2D PbS nanoplatelets (NPLs) form an emerging class of photoactive materials and have been proposed as robust materials for high-performance optoelectronic devices. However, the main drawback of PbS NPLs is the large lateral size, which inhibits their further investigations and practical applications. In this work, ultra-small 2D PbS NPLs with uniform lateral size (11.2 +/- 1.7 nm) and thickness (3.7 +/- 0.9 nm, approximate to 6 layers) have been successfully fabricated by a facile liquid-phase exfoliation approach. Their transient optical response and photo-response behavior are evaluated by femtosecond-resolved transient absorption and photo-electrochemical (PEC) measurements. It is shown that the NPLs-based photodetectors (PDs) exhibit excellent photo-response performance from UV to the visible range, showing extremely high photo-responsivity (27.81 mA W-1) and remarkable detectivity (3.96 x 10(10) Jones), which are figures of merit outperforming currently reported PEC-type PDs. The outstanding properties are further analyzed based on the results of first-principle calculations, including electronic band structure and free energies for the oxygen evolution reaction process. This work highlights promising applications of ultra-small 2D PbS NPLs with the potential for breakthrough developments also in other fields of optoelectronic devices.

Automated summary

In this study, ultra-small 2D PbS nanoplatelets (NPLs) with uniform size were successfully fabricated using a liquid-phase exfoliation approach. The NPLs-based photodetectors (PDs) showed excellent photo-response performance, with high responsivity and detectivity, outperforming current PEC-type PDs. The outstanding properties of the NPLs were further analyzed through first-principle calculations, indicating promising applications in optoelectronic devices and potential breakthrough developments in other fields.