Shape-controlled synthesis of Ag/CsPbBr Janus nanoparticles.

The poor light absorption of visible light for CsPbBr nanocrystals (NCs) has severely impeded their practical applications. Although the semiconductor/perovskite heterostructure holds great promise for enhancement in absorption, it has remained a serious challenge for synthesizing a semiconductor/perovskite heterostructure. In this work, monodispersed Janus heterostructures composed of CsPbBr decorated with either multiple Ag or single Ag on its surface (named as mAg/CsPbBr and sAg/CsPbBr respectively), are successfully prepared. The size of Ag seeds has an important effect on the shape of the products. Small-sized Ag seeds lead to the formation of mAg/CsPbBr Janus NCs, while relatively large-sized Ag seeds produce sAg/CsPbBr Janus NCs. It is noted that this work not only provides a novel method for the modification of individual CsPbBr NCs, but also enhances the absorption of the CsPbBr in the visible region, indicating great potential for optoelectronic applications, such as photocatalysis and solar cells.