A New Anthracene-based Small Molecule as Cathode Interlayer for Efficient Polymer Solar Cells

A new small molecule with excellent electron‐transporting property, namely 9,10‐bis(2‐(N‐octyl‐1,8‐naphthalimid‐4‐yl)ethynyl)anthracene (BNA), is prepared and characterized. A polymer solar cell (PSC) based on poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenylC61 ‐butyricacidmethyl ester (PC61BM) is also fabricated by using BNA as the cathode buffer layer between the Al electrode and photoactive layer, and their influence on the performance of the PSCs is investigated. It is found that the open‐circuit voltage (V oc ), short‐circuit current density (J sc ), and power conversion efficiency (PCE) of a device with a 6‐nm BNA layer improved to 0.63 V, 9.74 mA/cm2, and 3.74%, respectively, which correspond to an increase of 53.6%, 38.0%, and 177% compared to those without the buffer layer. The BNA buffer layer could effectively improve the interfacial contact performance between the Al electrode and photoactive layer, decrease the series resistance, and improve the collection efficiency of carriers. The devices with appropriate thickness of the BNA buffer layer can also replace the common low‐work‐function metal Ca for increasing the PCE and lifetime of PSCs.