组分对Cu-Zn-In-S/ZnS核壳量子点发光性能的影响

Effects of Composition on Photoluminescence Properties of Cu-Zn-In-S/ZnS Core/shell Quantum Dots

利用热注射法通过调控Cu/Zn比例制备了不同组分的Cu-Zn-In-S/ZnS核壳量子点,通过紫外-可见吸收光谱以及稳态和时间分辨光谱分析Cu/Zn比例对量子点发光性能的影响.结果表明,不同组分Cu-Zn-In-S/ZnS核壳量子点呈现闪锌矿结构且晶粒尺寸接近;随着Cu/Zn比例的减小,Cu-Zn-In-S/ZnS核壳量子点的带隙变宽,导致吸收光谱发生蓝移;当Cu/Zn比例从6/1减小到1/6时,量子点的发光峰位从640nm蓝移529nm.由于Zn2+替代Cu+能够减少Cu原子缺陷的形成,从而提高了量子点的荧光效率;当Cu/Zn=1/6时,样品中观测到Cu+离子发光和较长的荧光寿命.

Cu-Zn-In-S/ZnS core/shell quantum dots （QI）s） with various Cu/Zn molar ratios were synthesized by a hot-injection method. The effects of Cu/Zn ratios on the photoluminescence （PL） properties of Cu-Zn-In-S/ZnS core/shell QDs were investigated by UV-vis absorption, steady-state, and time-resolved PL spectroscopy. It could be observed that the Cu-Zn-In-S/ZnS QDs with various Cu/Zn ratios exhibited zinc blende structure and similar grain sizes. The blue shift in absorption onset of Cu-Zn- In-S/ZnS core/shell QDs increased with reducing Cu/Zn ratios, resulting from widened bandgap of the QDs due to the difference in QD composition. The corresponding emission wavelength of QDs was also blue-shifted from 640 nm to 529 nm when Cu/Zn ratios decreased from 6/1 to 1/6. The Cu-Znqn-S/ZnS core/shell QDs exhibited an enhanced PL quantum yield with decreasing Cu/Zn ratios because Zn2＋ substituting Cu＋ could inhibit the defect formation of Cu interstitial atoms. In addition, Cu＋ ions emission is observed in the sample with Cu/Zn=1/6, companying with longer PL lifetime.