Heterojunctions Formed on the Nanocrystalline Interfaces Between Organic Molecules and Hybrid Perovskites

We report heterointerfacial construction in the cocrystallization structures of a green‐emitting perovskite and a red‐emitting small‐molecular semiconductor, where blend nanocrystal clusters were produced between CH 3 NH 3 PbBr 3 (MAPbBr 3 ) and N , N ’‐bis(1‐ethylpropyl)−3,4,9,10‐perylenetetracarboxdiimide (EPPTC) using solution processible method. The blend film was prepared by dropping the EPPTC/chloroform solution onto the spin‐coating CH 3 NH 3 PbBr 3 /DMF solution at a delay of 8 s. The concentrations of both solutions have also been optimized, so that a crystallization pattern was achieved with EPPTC stacked in the center and MAPbBr 3 extends on the outer ring. The formation of heterojunctions is evidenced not only by the microscopic characterization, but also by new features in the photoluminescence spectrum. The mechanisms for electronic transitions on the heterointerfaces were resolved and more clearly verified by the decay dynamics of the emission within a largely redshifted band.