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

TLDR

The 2D PbS nanoplatelets are emerging photoactive materials for high‑performance optoelectronics, yet their large lateral size limits practical applications. The study aims to fabricate ultra‑small 2D PbS NPLs with uniform lateral size and thickness via liquid‑phase exfoliation. The authors produce the NPLs by liquid‑phase exfoliation and evaluate their transient optical response and photo‑electrochemical behavior using femtosecond‑resolved transient absorption and PEC measurements, supported by first‑principle calculations of band structure and oxygen‑evolution energetics. The resulting photodetectors exhibit UV‑to‑visible photo‑responsivity of 27.81 mA W⁻¹ and detectivity of 3.96 × 10¹⁰ Jones, outperforming existing PEC‑type PDs, and the work highlights the potential of ultra‑small 2D PbS NPLs for breakthrough optoelectronic devices.

Abstract

Abstract 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, ≈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 × 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.