Inkjet Printing of Heterostructures: Investigation and Strategies for Control of Interfaces

Development of printed electronics requires understanding and control of the interfaces in heterostructure devices. However, investigation of the interfaces between dissimilar materials to achieve control of intermixing presents challenges. Here, we report investigation of interfaces in inkjet printed heterostructures by time-of-flight secondary ion mass spectrometry (ToF-SIMS), focused ion beam scanning electron microscopy (FIB-SEM), and energy dispersive X-ray (EDX) analysis to provide complementary insights into the intermixing phenomena. By examining various heterostructures of 0D (CsPbBr₃ nanocrystal), 2D (inkjet printed graphene, iGr), and polymeric (PEDOT:PSS) materials deposited with different printing parameters, we established the effect of ink composition and printing parameters on the intermixing depth. We demonstrated that in the heterostructures where the intermixing is dominated by layer porosity, the intermixing depth does not affect the electrical properties of the device, while intermixing by layer redispersion results in the decrease of the effective layer thickness accompanied by an increase of electrical resistance. The strategy for control over the interfacial composition and morphology in printed heterostructures could enable improved design and performance of printed devices.