Heterostructures of 3D/2D Perovskites with Sharp Interfaces for High-Performance Photovoltaics and Light Emitting Diodes

Heterostructures are created by combining two different materials and are the building blocks for the advanced semiconductor devices that are being used today such as multijunction photovoltaics and light emitting diodes and lasers. Halide perovskites have emerged as a new class of semiconductors and have demonstrated near-ideal properties, which have led to high effiiciency optoelectronic devices. However, despite more than a decade of progress, it has been challenging to create heterostructures with sharp interfaces and arbitrary thickness between two perovskites (3D/3D or 3D/2D largely due to solvent incompatibility, which destroys or degrades the underlying perovsite.<br/>We have developed a novel approach to create heterostructures of 3D/2D perovskites with arbitrary thickness and chemical composition for 3D or 2D perovskites. Characterization of the 3D/2D interface using ToF-SIMS, angle dependent GIWAX, absorbance and photoluminescence reveal the presence of a phase-pure 2D perovskite with an interface sharpness of &lt;10 nm. By tailoring the band-alignment between the 3D and 2D heterointerfaces, we show that we can use the 2D perovskite as either a hole of electron transport layer. Moreover, tuning the 2D perovskite also allows us to create either a type I or type II heterstrostructures. Finally, we demonstrate photovoltaic devices with 23% efficiency and LEDs with &gt;10% EQE with excellent stability.