Deterministic Monolayer Manipulation of Single-Crystalline Ruddlesden-Popper Halide Perovskite for Opto-Electronic Device Array Fabrication

Ruddlesden-Popper perovskite (RPP), a quasi two-dimensional phase of organic-inorganic hybrid halide perovskites have been considered as promising candidates for next generation opto-electronic applications. In addition to their broad controllability of bandgap between 2 and 3 eV, their inert surface nature can realize high-performance optoelectronic devices even at nanometer scale. Moreover, phase-pure monocrystalline RPPs can be synthesized by using solution processes, which exhibit significantly enhanced optoelectronic characteristics. However, the multi-layer structure of fabricated RPP crystals and the high solubility in typical solvents have been major challenges to obtain monolayer RPP for device fabrication. Conventional layer splitting and photolithography-based patterning processes which involves solvents are incompatible with RPPs. Therefore, a dry process for monolayer manipulation of RPP must to be established to realize nanoscale device array.<br/>In this contribution, we develop a novel all-dry layer manipulation process through adhesion control of RPP. We first synthesize inch-scale phase-pure monocrystalline RPP crystals. Using the RPP crystals, we characterize the adhesion between RPP and various inorganic materials for adhesion layer by using atomic force microscopy. We find out that adhesion between RPP and inorganic materials surface can be tailored depending on the surface roughness as well as the material of adhesion layer. We investigate the fracture mechanics of RPP monolayers by measuring the out-of-plane adhesion to in-plane toughness ratio. Simultaneous processes of deterministic monolayer spitting and lateral patterning with micrometer-scale resolution are demonstrated. Furthermore, we demonstrate RPP monolayer photodetector array fabricated by the developed monolayer manipulation process.