| dc.description.abstract | Hybrid organic-inorganic perovskites have drawn much attention over the past decade because of their excellent electrical properties, which have allowed for their implementation in photovoltaics, optoelectronics, and other device applications. Within the broader class of hybrid organic-inorganic perovskites, there are subclasses based on the dimensionality and structure of the perovskite material. One notable subclass is the 2 dimensional Ruddlesden-Popper perovskite family. 2D Ruddlesden-Popper perovskites exhibit high quantum confinement due to their layered quantum well structure. The 2D Ruddlesden-Popper phase perovskites have also drawn significant attention due to their superior ambient stability compared to their 3D counterpart. The broad 2D class of semiconducting materials have also garnered much intrigue since the discovery of graphene for ultra-thin devices with exceptional performance. One bottleneck to increasing the efficiency of 2D semiconducting material and perovskite based devices is non-radiative recombination losses and charge scattering caused by defects and charge perturbations at contact interfaces. In this work, I identify an effective methodology which can be used to study the charge screening behaviors of 2D Ruddlesden-Popper perovskites. Using kelvin probe force microscopy, the surface potential, which is affected by charge transfer and perturbations, can be mapped for 2D perovskite samples of various thicknesses thereby giving insights to the charge screening lengths of the various perovskite materials. This work investigates the charge screening behavior of C4n1, C4n2, C4n3, and C4n5 2D perovskites. Results show trends of increasing charge screening behavior with layer number for each perovskite sample. Furthermore, it is shown that higher n-number 2D perovskite samples are more effective at screening charge perturbations compared to the low n-number perovskites. Overcoming the hurdle of charge transfer efficiency losses due to charge perturbations at interfaces is crucial to enabling the engineering of more efficient perovskite devices. Future studies using this methodology can be used to identify how charge screening behavior depends on the organic ligands of various 2D perovskites. | |
