Solution‐Processable 2D Materials Applied in Light‐Emitting Diodes and Solar Cells

The last decades have witnessed a remarkable scientific progress in the field of organic and perovskite optoelectronics. Two‐dimensional (2D) materials are an attractive building block for next‐generation devices, thanks to their unique physical, optical, and electric characteristics including atomically thin bodies, high transmittance, ultralight weight, and tunable band structures. The state‐of‐the‐art optoelectronic devices utilizing 2D materials mainly rely on 2D thin films grown by chemical vapor deposition. Although good device performances have been demonstrated, a huge gap between fundamental studies and practical applications remains, because of the high cost and troublesome transfer/restacking processes. Therefore, flexible and transparent light‐emitting diodes (LEDs) and solar cells (SCs) containing solution‐processed 2D materials from top‐down exfoliation methods have recently emerged as promising candidates for future light conversion and emission devices. They combine ease of processing, tailorable optoelectronic features, facile integration with complementary layers, compatibility with arbitrary substrates, and enhanced performances. In addition, the latest processing techniques (such as ink‐jet printing, spray coating) also offer the opportunity for the scaled‐up fabrication of square‐meter‐scale low‐cost device systems. Recent advances, challenges, and future perspectives of solution‐processed 2D materials for usage in emerging LEDs and SCs applications are discussed here. The outstanding optical and electric properties of 2D materials make them suitable for optoelectronic applications. Solution‐processable top‐down exfoliation methods offer ease of processability and properties tailoring. An overview of organic and perovskite devices, such as solar cells and light‐emitting diodes, based on solution‐processed 2D materials is presented. Further, opportunities and challenges toward their practical integration are also discussed.