Proceedings of International Conference on Perovskite and Organic Photovoltaics and Optoelectronics (IPEROP19)
DOI: https://doi.org/10.29363/nanoge.iperop.2019.083
Publication date: 23rd October 2018
A crucial issue facing polymer-based solar cells is how to maximize short-circuit current density (Jsc) and open-circuit voltage (Voc) at the same time and thus the power conversion efficiency. A key to resolving the issue is to reduce the relatively large photon energy loss, which is defined by the difference between the optical bandgap of the material and Voc. Here, I will show that a semiconducting polymer based on naphthobisoxadiazole (PNOz4T) [1], having a narrow bandgap of 1.52 eV, can give high Voc of approximately 1 V with relatively high efficiencies of more than 8%, when combined with PC71BM. As a result, the photon energy loss was found to be as small as 0.52 eV, which is much smaller than that of typical high performance polymer/fullerene systems and approaches the values of inorganic and perovskite solar cells. It is also interesting to note that the efficiency of the PNOz4T system is one of the highest values among the polymer/fullerene cells with such small photon energy loss.[2] I will also show ternary blend system with well controlled energetic alignment can give small photon energy loss of less than 0.5 eV.