A crucial issue facing polymer-based solar cells is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density and open-circuit voltage at the same time and thus the power conversion efficiency. Here we demonstrate that the use of a naphthobisoxadiazole-based polymer with a narrow bandgap of 1.52 eV leads to high open-circuit voltages of approximately 1 V and high-power conversion efficiencies of ~9% in solar cells, resulting in photon energy loss as small as ~0.5 eV, which is much smaller than that of typical polymer systems (0.7–1.0 eV). This is ascribed to the high external quantum efficiency for the systems with a very small energy offset for charge separation. These unconventional features of the present polymer system will inspire the field of polymer-based solar cells towards further improvement of power conversion efficiencies with both high short-circuit current density and open-circuit voltage.

Nature Communications 6, Article number: 10085 doi:10.1038/ncomms10085
Received 26 March 2015 Accepted 02 November 2015 Published 02 December 2015

http://www.nature.com/ncomms/2015/151202/ncomms10085/full/ncomms10085.html

对于聚合物太阳能电池来说，一个关键的问题是如何控制聚合物与富勒烯间的能量，以使短路电流密度和开路电压达到最大化，进而提升能量转化效率。 Kawashima 等人报道了一种基于萘并二恶二唑的聚合物太阳能电池体系，其带隙只有 1.52eV ，但开路电压接近 1V ，能量转化效率达到 9% 。这个电池的光能损失仅为 0.5eV ，远小于其他聚合物电池体系的光能损失（0.7-1.0eV）。这一结果主要归功于体系较高能外量子效率，以及较小的电荷分离能量补偿。作者称，这种不寻常的结果有助于未来聚合物太阳能电池效率的进一步提高。（新材料在线）