Handwriting of perovskite optoelectronic devices on diverse substrates

Paper and textiles that are commonly used in our daily lives hold great potential as platforms for next-generation flexible and wearable electronics. However, strategies for fabricating light-emitting diodes and photodetectors on different substrates are restricted in terms of their quantity and variety as strict flatness and smoothness are often required. Here we develop a highly versatile, scalable and eco-friendly handwriting approach to draw multicolour perovskite light-emitting diodes and perovskite photodetectors on various substrates, including paper, textiles, plastics, elastomers, rubber and three-dimensional objects. Our method uses common ballpoint pens filled with newly formulated inks of conductive polymers, metal nanowires and multiple perovskites for a wide range of emission colours. Just like writing with multicoloured pens, writing layer-by-layer with these functional inks enables perovskite optoelectronic devices to be realized within minutes. This process can be carried out by individuals without specialized training. The handwritten perovskite light-emitting diodes can exhibit a brightness as high as 15,225 cd m −2 , a current efficiency of 6.65 cd A −1 and a turn-on voltage of 2.4 V. The perovskite photodetectors exhibit an on/off ratio of over 10,000 and a responsivity of up to 132 mA W −1 . This work offers a route to the integration of perovskite optoelectronics in low-cost and large-area application scenarios such as electronic textiles, electronic paper, smart packaging and other disposable electronics and wearables.