Black Phosphorus Quantum Dots Used for Boosting Light Harvesting in Organic Photovoltaics

Although organic photovoltaic devices (OPVs) have been investigated for more than two decades, the power conversion efficiencies of OPVs are much lower than those of inorganic or perovskite solar cells. One effective approach to improve the efficiency of OPVs is to introduce additives to enhance light harvesting as well as charge transportation in the devices. Here, black phosphorus quantum dots (BPQDs) are introduced in OPVs as an additive. By adding 0.055 wt % BPQDs relative to the polymer donors in the OPVs, the device efficiencies can be dramatically improved for more than 10 %. The weight percentage is much lower than that of any other additive used in OPVs before, which is mainly due to the two‐dimentional structure as well as the strong broadband light absorption and scattering of the BPQDs. This work paves a way for using two‐dimentional quantum dots in OPVs as a cost‐effective approach to enhance device efficiencies. Strong light absorption: The power conversion efficiencies of organic photovoltaics have been improved by introducing black phosphorus quantum dots (BPQDs; 0.055 wt % relative to the donor polymers) due to the boosted light harvesting of the devices. The effect is attributed to the strong light absorption as well as the two‐dimensional structure of the BPQDs. A pronounced size effect of BPQDs on the performance enhancement is observed.