Rational Design of π-Extended Covalent Organic Frameworks for Enhanced Solar Energy Harvesting: Synthesis to Device Integration

Covalent organic frameworks (COFs) are functional and tunable backbones and pores, making them suitable for solar systems. The periodic donor-acceptor structures and host-guest configurations by porosity facilitate charge transfer and separation in photophysical processes. It has also been shown that porous organic polymers (POPs) play a crucial function in other important device components, including electrodes and hole-carrying layers. This review will mainly concentrate on the most recent developments in the use of POPs to improve the performance of solar cell devices, containing dye-sensitized solar cells, organic solar cells, and perovskite solar cells. The need for structural modifications for each type of energy conversion is examined, and common predesigning procedures for skeletons and channels are summarized. Artificial methods are presented for creating energy conversion functions, such as electro- and photocatalytic conversions. By revealing the interactions of COFs with electrons, holes, and photons, the aspects of energy conversions and the significance of structural classifications in energy conversions were further examined. To paint a complete image of energy conversions based on COFs, we have finally anticipated the difficult problems in molecular design and synthesis, considered future paths toward progression in this field, and shown perspectives from aspects of chemistry, physics, and materials science.