Charge Carrier Dynamics in Bandgap Modulated Covellite‐CuS Nanostructures

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-12, Vol.20 (49), p.e2405859-n/a
• Main Authors: Jagadish, Kusuma, Godha, Akshath, Pandit, Bidhan, Jadhav, Yogesh, Dutta, Arpita, Satapathy, Jyotiprakash, Bhatt, Himanshu, Singh, Balpartap, Makineni, Surendra Kumar, Pal, Shovon, Rondiya, Sachin R.
• Format: Article
• Language: English
• Subjects: Carrier density; Carrier lifetime; Carrier recombination; Conduction bands; copper sulfide; Copper sulfides; Covellite; Current carriers; cyclic voltammetry; Dopants; Electrochemical analysis; Electrode materials; Energy gap; Energy levels; flower morphology; Manganese; Metal sulfides; Semiconductors; Sodium-ion batteries; terahertz spectroscopy; transient absorption spectroscopy; Transition metals; Trapping; Valence band
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202405859

Copper Sulfide (CuS) semiconductors have garnered interest, but the effect of transition metal doping on charge carrier kinetics and bandgap remains unclear. In this study, the interactions between dopant atoms (Nickel, Cobalt, and Manganese) and the CuS lattice using spectroscopy and electrochemical analysis are explored. The findings show that sp‐d exchange interactions between band electrons and the dopant ions, which replace Cu2+, are key to altering the material's properties. Specifically, these interactions result in a reduced bandgap by shifting the conduction and valence band edges and increasing carrier concentration. It is observed that undoped CuS nanoflowers exhibit a carrier lifetime of 2.16 ns, whereas Mn‐doped CuS shows an extended lifetime of 2.62 ns. This increase is attributed to longer carrier scattering times (84 ± 5 fs for Mn‐CuS compared to 53 ± 14 fs for CuS) and slower trapping (∼1.5 ps) with prolonged de‐trapping (∼100 ps) rates. These dopant‐induced energy levels enhance mobility and carrier lifetime by reducing recombination rates. This study highlights the potential of doped CuS as cathode materials for sodium‐ion batteries and emphasizes the applicability of metal sulfides in energy solutions. Doping Copper Sulfide (CuS) with transition metals (Ni, Co, Mn) modifies its properties by sp‐d exchange interactions between band electrons and dopant ions, reducing the bandgap and increasing carrier concentration. Mn‐doped CuS exhibits a longer carrier lifetime, enhanced mobility, and reduced recombination rates, making it a promising candidate for energy applications.