We present a universal direct photocatalytic patterning method that can completely preserve the optical properties of perovskite nanocrystals (PeNCs) and other emissive nanomaterials. Solubility change of PeNCs is achieved mainly by a photoinduced thiol-ene click reaction between specially tailored surface ligands and a dual-role photocatalytic reagent, pentaerythritol tetrakis(3-mercaptopropionate) (PTMP), where the thiol-ene reaction is enabled at a low light intensity dose (~ 30 millijoules per square centimeter) by the strong photocatalytic activity of PeNCs. The photochemical reaction mechanism was investigated using various analyses at each patterning step. The PTMP also acts as a defect passivation agent for the PeNCs and even enhances their photoluminescence quantum yield (by ~5%) and photostability. Multicolor patterns of cesium lead halide (CsPbX 3 )PeNCs were fabricated with high resolution (<1 micrometer). Our method is widely applicable to other classes of nanomaterials including colloidal cadmium selenide–based and indium phosphide–based quantum dots and light-emitting polymers; this generality provides a nondestructive and simple way to pattern various functional materials and devices.

A coexistence of the areas in separate nanocrystallites with different spatial structures having smooth coherent interface was shown by the direct observation using the techniques of high resolution transmission electron microscopy (HRTEM). Results confirm the model of a nanoparticle as an intermediate state of condensed matter in nanometer scale between clusters and bulk crystals. Particularities of phase transformations in polymorphous YSZ nanopowder and changes of its nanocrystallite state induced by powerful ultrasonic activation were studied.

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