Light Management in Organic Photovoltaics Processed in Ambient Conditions Using ZnO Nanowire and Antireflection Layer with Nanocone Array
Abstract
Low carrier mobility and lifetime in semiconductor polymers are some of the main challenges facing the field of organic photovoltaics (OPV) in the quest for efficient devices with high current density. Finding novel strategies such as device structure engineering is a key pathway toward addressing this issue. In this work, the light absorption and carrier collection of OPV devices are improved by employment of ZnO nanowire (NW) arrays with an optimum NW length (50 nm) and antireflection (AR) film with nanocone structure. The optical characterization results show that ZnO NW increases the transmittance of the electron transporting layer as well as the absorption of the polymer blend. Moreover, the as-deposited polymer blend on the ZnO NW array shows better charge transfer as compared to the planar sample. By employing PC70BM:PV2000 as a promising air-stable active-layer, power conversion efficiencies of 9.8% and 10.1% are achieved for NW devices without and with an AR film, indicating 22.5% and 26.2% enhancement in PCE as compared to that of planar device. Moreover, it is shown that the AR film enhances the water-repellent ability of the OPV device.
M.M.T. and H.T.D. contributed equally to this work. This work was sponsored by ENI S.p.A under the MITEI Solar Frontier Center. M.H.T.D. acknowledges postdoctoral fellowship support from the Natural Sciences and Engineering Research Council (NSERC) of Canada. M.M.T. thanks the Hong Kong University of Science and Technology. K.E.S. and M.G.B. acknowledge the United States Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering (Award No. DE‐FG02‐07ER46454). N.D.K. and M.G.B. acknowledge the National Science Foundation Graduate Research Fellowship Program.
