Breaking the symmetry of colloidal 2D nanoplatelets:Twist induced quantum coupling

Twist provides a new degree of freedom for nanomaterial modifications,which can provide novel physical properties.Here,colloidal two-dimensional(2D)twisted CdSe nanoplatelets(NPLs)are successfully fabricated and their morphology can change from totally flat to edge-twisted,and then to middle-twisted with prolonged reaction time.By combining experiments and corresponding theoretical analyses,we have established the length-dependent relationships between the surface energy and twist,with a critical lateral dimension of 30 nm.We found that the defects formed during the synthesis process play a vital role in generating intense stress that develops a strong torsion tensor around the edges,resulting in edge-twisted and final middletwisted NPLs.Furthermore,due to the geometric asymmetry of twisted NPLs,the dissymmetry factor of single particle NPLs can reach up to 0.334.Specifically,quantum coupling occurs in middle-twisted NPLs by twisting one parent NPL into two daughter NPLs,which are structurally and electronically coupled.This work not only further deepens our understanding of the twist mechanism of 2D NPLs during colloidal synthesis,but also opens a pathway for applications using twistronics and quantum technology.

Perovskite quantum dot microarrays:In situ fabrication via direct print photopolymerization

Quantum dots color conversion(QDCC)is considered as a facial and versatile way to achieve full-color organic light emitting diode(OLED)and micro-LED display due to the wide color gamut performance and easy integration.However,the aggregation of QDs and coffee-ring effects after solvent evaporation lowers the light conversion efficiency and emission uniformity in QDs microarrays,raising blue-light leakage or optical crosstalk.Here,we report the fabrication of perovskite quantum dots(PQDs)microarrays by combining the inkjet printing and in situ fabrication of PQDs during the photopolymerization of precursor ink.The resulting PQDs microarrays exhibit three-dimensional(3D)morphology with hemisphere shape as well as strong photoluminescence,which is desirable for QDCC applications.We demonstrate the dominant role of ultraviolet(UV)curable precursors and surface functionalized substrate in controlling the shape of microarrays,where significantly increased contact angle(100°)and large height to diameter ratio(0.42)can be achieved.We further demonstrate the potential use of the in situ direct print photopolymerization method for fabricating large-area multicolor patterned pixel microarrays with a wide color gamut and high resolution.The fabrication of 3D PQDs microarrays opens up new opportunities in a variety of applications including photonics integration,micro-LED,and near-field display.