Colloidal quantum dot for infrared-absorbing solar cells: State-of-the-art and prospects

Colloidal quantum dot (CQD) shows great potential for application in infrared solar cells due to the simple synthesis techniques, tunable infrared absorption spectrum, and high stability and solution-processability. Thanks to significant efforts made on the surface chemistry of CQDs, device structure optimization, and device physics of CQD solar cells (CQDSCs), remarkable breakthroughs are achieved to boost the infrared photovoltaic performance and stability of CQDSCs. In particular, the CQDSC with a high power conversion efficiency of ~ 14% and good stability is reported, which is very promising for infrared-absorbing solar cells. In this review, we highlight the unique optoelectronic properties of CQDs for the development of infrared-absorbing solar cells. Meanwhile, the latest advances in finely controlling surface properties of CQDs are comprehensively summarized and discussed. Moreover, the device operation of CQDSCs is discussed in-depth to highlight the impact of the device structure optimization of CQDSCs on their photovoltaic performance, and the emerging novel types of CQDSCs, such as semitransparent, flexible, and lightweight CQDSCs, are also demonstrated. The device stability of CQDSCs is also highlighted from the viewpoint of practical applications. Finally, the conclusions and possible challenges and opportunities are presented to promote the development steps of the CQDSCs with higher infrared photovoltaic performance and robust stability.