Novel Direct Nanopatterning Approach to Fabricate Periodically Nanostructured Perovskite for Optoelectronic Applications

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com 1606525 (1 of 10) Conventionally, optoelectronic devices adopt planar perovskite configurations. Compared with planar thin films, nanostructured semiconductors offer unique optical properties. In photovoltaics, semiconductor gratings integrated with metal electrodes have been utilized to excite surface plasmons[6] and increase light path length[7] within semiconductors for improving the power conversion efficiency of corresponding solar cells. In addition, periodic nanostructures have been incorporated in LEDs to enhance light extraction.[8] Moreover, distributed feedback lasers[9] and photonic crystal lasers[10] have been realized through precisely designing semiconductor periodic nanostructures. Recently, an indirect patterning approach has been adopted to prepare perovskite nanostructures. This approach starts with patterning substrates, such as glass,[11] quartz,[12] silicon,[13] and Si3N4 through electron-beam lithography or photolithography. Perovskite will then be fabricated on the patterned substrate. This indirect patterning approach typically requires relatively complicated processes and thus a higher fabrication cost.[15] Alternatively, a direct patterning approach is likely to simplify the device fabrication process and reduce the cost.[16] However, the difficulty of directly nanopatterning perovskite is that perovskite is very sensitive to polar solvents[17] such as water, methanol, and acetone, as well as high-temperature environments.[18] For instance, the direct patterning of perovskites through electron-beam lithography would lead to the unexpected phase transformation or defect of perovskite due to local heat induced by high-energy electrons.[19] Gas-assisted focused-ion beam etching[15] has been reported to eliminate the damage of perovskite during etching. Nevertheless, there is concern over the reduced photoluminescence (PL) of the patterned perovskite compared with the pristine planar one, which indicates that the film quality of the patterned perov skite is degraded. Consequently, it is still challenging to realize a simple and low-cost direct nanopatterning approach to fabricate periodic perovskite nanostructures with high crystal quality and good optical properties. Novel Direct Nanopatterning Approach to Fabricate Periodically Nanostructured Perovskite for Optoelectronic Applications