CsPbI3钙钛矿量子点的精细纯化及其高效发光二极管的研究

钙钛矿量子点发光二极管(QLEDs)因其色纯度高、颜色控制精准、色域广以及溶液可加工等特点,在显示和照明等领域有着极大的应用前景.针对红光钙钛矿CsPbI3量子点纯化过程中相变和表面配体损失造成的荧光退化问题,本工作发展了一种甲苯和乙酸乙酯协同的混合溶剂纯化策略,能够避免纯化过程中的相变问题,获得了纯立方相的CsPbI...

CsPbI3Perovskite Quantum Dots:Fine Purification and Highly Efficient Light-emitting Diodes

Perovskite quantum dot light-emitting diodes(QLEDs)possess the characteristics of high color purity,precise color control,wide gamut,and solution processibility,which shows great prospects in displays and lightings.However,red CsPbI₃quantum dots(QDs)are prone to luminescence degradation due to the thermal non-equilibrium-induced phase transition and ligand loss during the purification process.The purification of CsPbI₃QDs is more difficult than that of CsPbBr3 QDs.Because the ligands on the surface of the quantum dots will be lost continuously during the purification process,resulting in aggregation and transformation toδ-CsPbI₃phase.Aiming at this problem,We prepared the CsPbI₃QDs through a hot-injection method at 180℃.The original solution of the perovskite QD also contains impurities such as octadecene solvent,oleic amine,and oleic acid ligand,which will seriously affect the photoelectric properties and destroy the film.So we used different flocculation solvents and dispersion solvents to collaboratively purify the QDs.At last,our work developed a mixed-solvent purification strategy with toluene and ethyl acetate,which can avoid the phase transition during the purification process and lead to pure cubic CsPbI₃QDs.But when we do not add the additional ligands in purification process,the photoluminescence quantum yield(PLQY)of QDs will be far less than 100%.In order to enhance the PLQY,a ligand compensation strategy of using oleylammonium iodide(OAmI)to control the surface state of QDs was proposed,which reduced the surface defects and solved the problem of luminescence quenching caused by ligand loss.We found that 400μL OAmI enabled quantum dots to have both high PLQY of 70%and excellent electrical properties.Under electrically driven,the exciton recombination probability was significantly increased,and the CsPbI₃-based QLED achieved a maximum luminance of 3090 cd/m2 and a maximum external quantum efficiency(EQE)of 15.67%.The proposed fine purification strategy of CsPbI₃QDs has an important guiding significance for the development of high-efficiency QD materials and high-performance optoelectronic devices.