Inorganic Nanopillar Arrays Significantly Enhance Optoelectronic Functions, Environmental Stability and Mechanic Robustness of Flexible Perovskite Optoelectronic Devices

One-dimensional (1D) nanostructure arrays can reduce light reflection loss, suppress recombination dynamics, guide charge carrier transport, and relax stress and strain in flexible optoelectronic devices, to improve optoelectronic functions and stability under aging and mechanical bending. However, <i>in-situ</i> fabrication of 1D nano-arrays on polymer-based flexible electrodes is challenging, mainly due to degradation of polymer-based electrodes at high temperature of <i>in-situ</i> growth. <br/>Here, nanopillar arrays (NaPAs) made of diverse inorganic materials, such as Ti, TiO₂, SnO_x (functioning as electron transporting layers) and NiO_x (serving as hole transporting layers), are deposited onto a flexible electrode by glancing angle deposition (GLAD), to create perovskite solar cells (PSCs) and photodetectors. As-grown NaPAs enhance light transmittance, facilitate light harvesting in perovskite, promote charge carrier transport and collection, and facilitate the formation of large perovskite grains. All these features lead to high efficiency of &gt;20% and &gt;17% for the rigid and flexible PSCs, respectively. No obvious crack nucleation is formed on the NaPAs after 500 bending, resulting in good mechanic robustness and environmental stability of photovoltaic performance. Large-area (1 cm²) flexible PSCs containing the SnO₂ NaPAs show the champion power conversion efficiency (PCE) of 14.9%, which undergoes only 10% degradation for approximately 800 h storage and 20% degradation by manual bending for around 400 times. Furthermore, compared to the conventional mesoporous counterparts, metallic oxide NaPAs enable the perovskite photodetectors to comprehensively enhance the detection speed, responsivity, and detectivity, and to extend the linear dynamic range.<br/>We devise an advanced technique of low-substrate-temperature GLAD generally adapted to <i>in-situ</i> deposition of charge carrier transporting layers made of inorganic NaPAs on flexible electrodes, to significantly enhance optoelectronic performance, mechanic robustness, and environmental stability of flexible optoelectronic devices.