Controlling size of lead halide perovskite nanocrystals and their distance onto conductive supports by exploiting block copolymers self-assembly

The properties of devices based on perovskite nanocrystals (NCs) thin films critically depend on the size, morphology and nanoscale arrangement of NCs that can influence and improve the photophysical properties of perovskite. We present a simple method based on block copolymers (BCPs) self-assembly to fabricate nanostructured thin films, onto solid conductive supports, characterized by a controlled positioning of lead halide perovskite NCs at nanoscale. In particular, spherical micelles of polystyrene-b-poly(4-vinylpyridine) (PS-PVP) BCPs were used as nanoreactors for the synthesis of CsPbBr3 nanocrystals and as templates to control the organization of NCs onto conductive solid supports. We used indium tin oxide (ITO), tin oxide-coated ITO (ITO + SnO2) and nickel oxide-coated ITO (ITO + NiO), largely used in optoelectronic and photovoltaic devices, as conductive supports. This strategy results in a selective infiltration of perovskite NCs into spherical micelles of the BCP and consequent defined positioning of NCs onto the conductive supports. Moreover, we demonstrated that using two different PS-PVP copolymers characterized by different molecular masses of both PS and PVP blocks, it is possible to regulate the size of nanoclusters of perovskite NCs and their distance onto the solid supports at nanoscale. This confirms the high versatility of BCPs in fabricating materials with controlled morphology at nanoscale, which offers an opportunity to tune the properties of the final material.