Pejova Biljana, do Nascimento Julio A, Talbi Fayzah, Fawcett-Houghton Thomas Jack, Kerrigan Adam, Lari Leonardo, Douthwaite Richard E, Pejov Ljupcho, Lazarov Vlado K
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, SS. Cyril and Methodius University, POB 162, 1000 Skopje, North Macedonia.
School of Physics Engineering and Technology, University of York, York, YO10 5DD, UK.
Nanoscale. 2025 Jul 31;17(30):17846-17861. doi: 10.1039/d5nr01665g.
In this work, we demonstrate the colloidal bottom-up synthesis of spinel AgInS quantum dots (QDs) with tunable optical properties. The QD size, and consequently their band gap energy (), is effectively controlled by reaction temperature and ultrasound (US) irradiation. Under combined conditions of 75 °C and US irradiation, ultrasmall QDs with an average size of 2.6 nm are obtained, exhibiting a wide band gap of 3.77 eV. In the absence of US, reactions conducted at 55 °C and 75 °C yield larger QDs (∼5 nm and 31 nm, respectively), with reduced band gaps of 3.09 eV and 2.18 eV. The elevated temperature (75 °C) suppresses sulfur-chain formation that otherwise limits growth at 55 °C, while acoustic cavitation induced by US enables narrowest size distribution. Annealing of as prepared QDs, at 200 °C for 2 h, promotes coalescence resulting in QDs with increased size of ∼34 nm, with a bulk like band gap of 1.73 eV for QDs prepared without US. In contrast, annealing of the QDs, prepared with US, results in polycrystalline QDs with average size of ∼21 nm. High-resolution transmission electron microscopy reveals a strong correlation between QD size, structural ordering and optical behavior. The as-prepared 2.6 nm QDs exhibit lower Urbach energy, attributed to their single-crystalline nature, unlike the less ordered QDs synthesized without US. Annealing improves structural ordering and reduces Urbach energy in QDs prepared at 75 °C, while stacking faults and grain boundaries in other QDs hinder such improvements. Photoluminescence measurements further confirm a strong relationship between QD structure, size, and emission characteristics. The synthesized AgInS QDs exhibit remarkable band gap tunability of up to 2 eV across the visible spectrum and sharp band-edge emission, underscoring their potential for applications in optoelectronic and biomedical devices. This work provides a robust and sustainable pathway to high-performance, non-toxic QDs, addressing a key bottleneck for their use in biocompatible and consumer electronics.
在这项工作中，我们展示了具有可调光学性质的尖晶石型硫化银铟量子点（QDs）的胶体自下而上合成方法。量子点的尺寸，进而其带隙能量（），可通过反应温度和超声（US）辐照有效控制。在75°C和超声辐照的组合条件下，可获得平均尺寸为2.6 nm的超小量子点，其显示出3.77 eV的宽带隙。在没有超声的情况下，在55°C和75°C进行的反应产生更大的量子点（分别约为5 nm和31 nm），带隙减小至3.09 eV和2.18 eV。升高的温度（75°C）抑制了硫链的形成，否则硫链会限制在55°C时的生长，而超声引起的声空化使尺寸分布最窄。将制备好的量子点在200°C退火2小时，会促进聚结，导致量子点尺寸增加至约34 nm，对于未使用超声制备的量子点，其具有类似体材料的1.73 eV带隙。相比之下，使用超声制备的量子点退火后会得到平均尺寸约为21 nm的多晶量子点。高分辨率透射电子显微镜揭示了量子点尺寸、结构有序性和光学行为之间的强相关性。与未使用超声合成的无序程度较低的量子点不同，制备的2.6 nm量子点由于其单晶性质而表现出较低的乌尔巴赫能量。退火改善了在75°C制备的量子点的结构有序性并降低了乌尔巴赫能量，而其他量子点中的堆垛层错和晶界阻碍了这种改善。光致发光测量进一步证实了量子点结构、尺寸和发射特性之间的强关系。合成的硫化银铟量子点在可见光谱范围内表现出高达2 eV的显著带隙可调性和尖锐的带边发射，突出了它们在光电器件和生物医学器件中的应用潜力。这项工作为高性能、无毒的量子点提供了一条稳健且可持续的途径，解决了它们在生物相容性和消费电子产品中应用的一个关键瓶颈。
