Superior Visible Photoelectric Response with Au/Cu₂NiSnS₄ Core–Shell Nanocrystals

Abstract

The incorporation of plasmonic metal nanostructures into semiconducting chalcogenides in the form of core−shell structures provides a promising approach to enhancing the performance of photodetectors. In this study, we combined Au nanoparticles with newly developed copper-based chalcogenides Cu 2 NiSnS 4 (Au/CNTS) to achieve an ultrahigh optoelectronic response in the visible regime. The high-quality Au/CNTS core− shell nanocrystals (NCs) were synthesized by developing a unique colloidal hot-injection method, which allowed for excellent control over sizes, shapes, and elemental compositions. The as-synthesized Au/CNTS hybrid core−shell NCs exhibited enhanced optical absorption, carrier extraction efficiency, and improved photosensing performance owing to the plasmonic-induced resonance energy transfer effect of the Au core. This effect led to a significant increase in the carrier density of the Au/CNTS NCs, resulting in a measured responsivity of 1.2 × 10 3 AW −1 , a specific detectivity of 6.2 × 10 11 Jones, and an external quantum efficiency of 3.8 × 10 5 % at an incident power density of 318.5 μW cm −2 . These results enlighten a new era in the development of plasmonic core−shell nanostructure-based visible photodetectors.

Novel Au/Cu2NiSnS4 Nano-Heterostructure: Synthesis, Structure, Heterojunction Band Offset and Alignment, and Interfacial Charge Transfer Dynamics

“…CZTS has been reported to be the best alternative for platinum (Pt) photocathode in dye-sensitized solar cells (DSSCs), and to date, CZTS­(Se) as absorber material has achieved a remarkable power conversion efficiency (PCE) of 12.6%, highlighting the incredible opportunities for PV application. Recently, it was reported that Ni substitution for Zn (i.e., Cu 2 NiSnS 4 ) assists in the effective spatial separation of charge carriers, generating stable and high photocurrent from solar illumination, and demonstrated a low conduction band offset of −0.12 eV with p-type conductivity. , The Cu 2 NiSnS 4 (CNTS) possesses an optimum optical gap of 1.35 eV and absorption coefficient of >10 4 cm –1 , which is favorable for optoelectronic applications. , Additionally, CNTS has structural and compositional flexibility, making it an ideal material for solar water splitting, supercapacitors, and battery applications . Recently, Deepika et al demonstrated for the first time the chemical route for synthesizing phase-pure and crystalline CNTS nanocrystals and studied their potential for energy applications …”

“…They also claimed that a strong heteroepitaxy can occur between Au and CZTS, 4d (111) Au ≈ 3d (100) CZTS wurtzite structure, and 4d (111) Au ≈ 5d (220) CZTS tetragonal structure, irrespective of their significant lattice mismatch . Very recently, Yen et al showed the inclusion of plasmonic Au with CNTS (core–shell) boosting the ultrahigh optoelectronic performance of photodetectors in the visible regime attributed to the enhanced optical absorption, carrier extraction efficiency, and improved photosensing performance owing to the plasmon-induced resonance energy transfer effect of the Au core-CNTS . Although Au-CNTS has enormous potential as other ecofriendly heterostructures, the profound understanding of the origin of photophysical processes in the Au-CNTS heterojunction needs more investigation.…”