Blue Quantum Dots Based On B-site Iron Doping And Its Highly Discrete Composite Film

In recent years,all-inorganic perovskite quantum dots?CsPb X₃QDs,X=Cl,Br,I?prepared by solution method have attracted the attention of scientists for their unique optical properties,ultra-high photoluescence quantum yield?PLQY?and simple synthesis process.Compared with the green CsPbBr₃QDs,the PLQY of blue CsPb?Br/Cl?₃QDs is relatively low,which makes the poor performance of blue QLED.At the same time,the surface ligand of the all-inorganic perovskite quantum dots will fall off under the conditions of heating,humidity and light,causing the fluorescence performance of the perovskite quantum dots decrease significantly.This thesis mainly studies the improvement of thermal stability by changing the surface all-ligand of perovskite quantum dots,and the Fe doping treatment to improve the PLQY of blue perovskite quantum dots,and the use of small molecular material C8-BTBT and perovskite quantum dots The high-dispersion blue light-emitting layer is prepared and used as a light-emitting layer material in blue QLED devices.The main contents are as follows:?1?By using the small molecule material thiophene-3-boronic acid?TBA?as a ligand,a tri-ligand structure is formed on the surface of perovskite quantum dots together with oleic oleylamine and oleic acid.As a short-chain small molecule material,the interaction of TBA and perovskite quantum dots is much stronger than that of oleic oleylamine and oleic acid,so the perovskite quantum dots will not be detached under heating conditions.On the surface of perovskite quantum dots,the aggregation phenomenon of perovskite quantum dots due to heating can be avoided.Experimental studies have shown that the all-inorganic perovskite quantum dot film with TBA acid as the ligand can still maintain 50%of the original perovskite quantum dots PLQY and50%fluorescence after heating at 120 degrees Celsius for 70 minutes?2?Through the doping of CsPb?Br/Cl?₃QDs with Fe ions,blue perovskite quantum dots with better optical performance are obtained.Because smaller Fe ions partially replace larger Pb ions,causing lattice shrinkage,thus reducing the surface defect states of quantum dots,and PLQY of Fe-CsPb?Br/Cl?₃QDs obvious improved.Besides,iron doping can also increase the average lifetime of blue CsPb?Br/Cl?₃QDs from 1.42 ns to 7.02 ns.In addition to reducing the surface defect state of perovskite quantum dots,iron doping can also improve the stability of blue perovskite quantum dots.After being stored in the refrigerator for 190 days,it still has 40%PLQY.We use Fe-CsPb?Br/Cl?₃QDs as the light-emitting layer and obtain a blue QLED with a brightness of 11.5 cd/m²,under the same process conditions,the brightness of QLED prepared by undoped perovskite quantum dots is only 0.5 cd/m².Subsequently,in order to improve the current injection efficiency,we use the small molecular with high-mobility material C8-BTBT and blue light perovskite quantum dots to form a highly discrete light-emitting layer,and use an inverted device structure,with high discrete quantum dots as the light-emitting layer Obtained 10.8 cd/m²blue QLED,and from the current comparison,it can be seen that due to the recombination of C8-BTBT,the injection ability of carriers is greatly improved.