Highly stoichiometry-deviating chalcopyrite quantum dots: synthesis and copper defects-correlated photophysical...

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Copper indium selenide (CISe) quantum dots (QDs) are infrared semiconductors with low toxicity and unique optical properties.
• Intrinsic point defects in CISe QDs play a significant role in their photophysical processes.

Purpose of the Study:

• To synthesize CISe QDs with varying stoichiometry and investigate the impact of atomic ratios on their photophysical properties.
• To elucidate the relationship between copper deficiency and photoluminescence shifts in CISe QDs.

Main Methods:

• Synthesis of CISe QDs with similar sizes but distinct, stoichiometry-deviating atomic ratios.
• Characterization of photoluminescence spectra and Raman activity.
• Identification of defect origins for luminescence.

Main Results:

• Se-rich precursor synthesis yielded Cu-deficient CISe QDs with unique photophysical properties.
• Photoluminescence exhibited a monotonic red shift from 680 to 775 nm with decreasing Cu/In ratio.
• Luminescence was attributed to copper vacancy and antisite defects.
• Observed Raman activity at 5.6, 6.9, and 8.7 THz assigned to Cu-Se, In-Se optical phonon modes, and surface modes.

Conclusions:

• Stoichiometry deviation, specifically copper deficiency, significantly influences the photoluminescence of CISe QDs.
• Copper vacancies and antisite defects are the primary sources of luminescence in these materials.
• The study provides insights into defect engineering for tuning optical properties of CISe QDs.