Enhanced optical response of InSe nanosheet devices decorated with CsPbX3 (X = I, Br) perovskite nanocrystals

The combination of several two-dimensional materials opens the door for the creation of cooperative nanodevices with functionalities that complement to each other and even compensate the weaknesses of the individual components. Two-dimensional indium selenide (InSe) shows one of the largest tunability bandgap found in two-dimensional materials with application in optoelectronics. However, the intrinsic out-of-plane luminescent dipolar nature limits its implementation in devices operating in vertical configuration. All-inorganic CsPbX3 (X = Br, I) cubic nanoparticles offer high absorption and emission quantum yields and great integrability with two-dimensional materials. Combining these two compounds, it is found that InSe-perovskite nano-heterostructures enhances the photoluminescence of the InSe side of the device, as compared to the bare InSe nanosheet, due to the multi-oriented down-shift light conversion mediated by the perovskite-nanocrystals. Similar nanostructures have been prepared by using Molybdenum Selenide (MoSe2), but a reduction of its photoluminescence is observed in this case due to its well-known in-plane dipole orientation.