Printable Organic and Perovskite Solar Cells for Clean Energy 

Minimizing energy loss and increasing the field factor are key aspects to transcend the current limitations on the performance of organic photovoltaics (OPV). However, an inherent limit has set for an organic bulk-heterojunction (BHJ) blends from prominent non-geminate recombination through non-radiative charge transfer states. Our recent study on charge recombination in BHJ and Planar-Mixed Heterojunction (PMHJ) blends comprising a crystalline polymer donor with Se-containing Y6-derived non-fullerene acceptors has shown both high photovoltaic internal quantum efficiencies and high external electroluminescence quantum efficiencies. Crystallographic and spectroscopic studies reveal that the pseudo-2D, fused-ring molecular acceptors are not only intrinsically highly luminescent but also meets the criteria in achieving intrinsically radiative recombination within the blend, by promoting delocalized excitons with much longer luminescent lifetime and reduced exciton binding energies. These results provide the important demonstration of radiative non-geminate charge recombination in efficient OPV blends to achieve PCEs close to 20%. Moreover, a new “Dilution Effect” concept is introduced to explain the commonly observed composition-dependent Voc and reduced photovoltage loss in highly efficient ternary-based devices due to significantly reduced phonon-electron coupling. At the end, several novel interface/additive engineering approaches will be discussed to demonstrate high PCE (~26%) could be achieved in inverted perovskite solar cells and very efficient lead-capturing from decomposed perovskite devices. Their applications in various clean energy generation fields will also be discussed.