Patterning of hybrid metal halide perovskite via printed molecular templates

Patterning metal halide perovskite thin films is a necessary pathway to expand their optoelectronic applications. However, developing a suitable patterning technique is challenging as conventional lithographic processes are either detrimental to the perovskite layer or lack compatibility with scalable fabrication processes used in the manufacturing of printed electronics. In this work, a complete bottom-up patterning method is proposed based on de-wetting from a hydrophobic molecular template, which constrains the perovskite ink to directly crystallize in selected hydrophilic regions. Octadecylphosphonic acid molecules are used as the hydrophobic template and are effectively transferred onto metal-oxide substrates via micro-contact printing. This allows for a low-cost, rapid, and scalable micron-scale patterning of perovskite thin films. Facile control over light transmittance is demonstrated by adjusting the amount of exposed area and the corresponding spectral shape changes shift the film's appearance toward being color-neutral. Finally, the method's scalability and versatility are shown by fabricating 25 cm² patterned films over rigid and flexible substrates.