Mass Transfer Printing of Metal-Halide Perovskite Films and Nanostructures.

Most methods of depositing perovskite films cannot meet the diverse requirements of real applications such as depositing films on various types of substrates, making patterns with different bandgaps for full-color display. Here, a robust mass transfer method of perovskite films and nanostructures is reported, meeting those requirements, by using an ultrathin branched polyethylenimine as interfacial chemical bonding layers. The transfer-printed perovskite films exhibit comparable morphology, composition, optoelectronic properties, and device performances with the counterparts made by optimized spin-coating methods. The perovskite light-emitting diodes (PeLEDs) using the transfer-printed films show decent external quantum efficiencies of 10.5% and 6.7% for red (680 nm) and sky-blue (493 nm) emissions, which are similar to the devices made by spin-coating. This robust transfer printing method also enables the the preparation of perovskite micropatterns with a high resolution up to 1270 pixels per inch. Horizontally aligned red and sky-blue perovskite microstripes are further obtained through multiple printing processes for white PeLEDs. This work demonstrates a feasible strategy for making perovskite films or micropatterns on various substrates for real applications in full-color display, white LEDs, lasing, etc.