Colossal Vacancy Effect of 2D CuInP₂S₆ Quantum Dots for Enhanced Broadband Photodetection

Abstract

Band engineering is an effective way to tune the physical and chemical properties of materials, leading to significant performance improvement. Herein, the first two-dimensional (2D) quaternary quantum dots (QDs), CuInP2S6 (CIPS) QDs, were successfully fabricated by the lithium intercalation method with a high yield of ∼29%. Importantly, the tuned band structure of CIPS was achieved by forming colossal lithium-induced phosphorus and sulfur vacancies, endowing CIPS QDs with stronger and broader optical absorbance, as well as higher conductivity. Therefore, CIPS QDs exhibit outstanding intrinsic optoelectronic performances toward broadband photodetection with a broadband photoresponse from 405 to 1550 nm, a photoresponsivity of 22.9 A/W, a detectivity of 3.65 × 108 Jones, and a response speed of 60 ms. Especially, such excellent performances can be realized in a simple device structure and ambient air, exceptionally different from most 2D QD-based photodetectors requiring a heterostructure, gate voltage, or vacuum condition. In addition, CIPS QDs retain outstanding photoresponse on curving flexible substrates and in imaging applications. This work provides a unique venue for band structure tuning to effectively manipulate materials’ optoelectronic properties and functionalities.

Ideal Photodetector Based on WS2/CuInP2S6 Heterostructure by Combining Band Engineering and Ferroelectric Modulation

“…Then, Ti/Au (10/60 nm) films were deposited onto the patterned substrate using electron beam evaporation (Ecopia, EB-400S). CIPS crystals were synthesized through a chemical vapor transport method, 53 while WS 2 crystals were obtained from Shanghai OnWay Technology Co., Ltd. Subsequently, a CIPS nanoflake and a WS 2 nanoflake were mechanically exfoliated from their respective bulk crystals and alternately dry transferred onto the bottom Ti/Au electrode.…”

High-Sensitivity Flexible Photodetectors Based on Bi2Te3/Rubrene Schottky Heterojunction with Superior Interface

“…Similar to the variation of the responsivity (R) of the device, the detectivity (D*) decreases monotonously with the continuous increase in the light power at each bias-voltage condition. The increased external biasvoltages have indeed improved the detectivity of the OIHPDs, and the highest D* value of 1.42 × 10 13 Jones was obtained at the bias voltage of −3.0 V.…”

“…The PDs that convert optical signals into electrical signals via different photorelated processes are essential components of modern electronic and optoelectronic industry. To meet certain performance criteria, various heterostructure PDs have been proposed using newly confirmed 2D materials, such as transition metal dichalcogenides (TMDs) and graphene. − In response to developing a high-efficiency 2D inorganic heterojunction with superior interface, extreme and critical growth conditions must be part of the procedures, especially for thermal growth techniques. Despite the larger interface-to-volume ratio generally contributing to the improved photon absorptivity of the device, the large interfacial leakage current, complex interfacial recombination processes of excitons, and Fermi-level pinning effect cannot be easily avoided for the 2D inorganic heterostructure PDs, caused by the interfacial atom diffusion effect after heat treatment processes.…”

Electronic and optical properties of chemically modified 2D GaAs nanoribbons

“…Decreasing the size of a material in a quantum dot leads to an increase in its electronic and optical energy gap 27 – 30 . Furthermore, the application potential of 2D-QDs can be significantly enhanced through chemical functionalization, which involves processes such as doping 31 , introducing vacancies 32 , 33 , or attaching chemical groups 34 – 37 . The ability to tailor the physical and chemical properties of these nanodots using these approaches has greatly expanded their range of applications.…”