Solution-Processed Copper Iodide as an Inexpensive and Effective Anode Buffer Layer for Polymer Solar Cells

In this work, a CuI anode buffer layer prepared from a facile solution-processed method was introduced in polymer solar cells (PSCs). The CuI films obtained under different spin-coating speeds and anneal treatments, and the performances of corresponding device fabricated with these CuI films were systematically investigated. The results showed that the devices based on CuI anode buffer layer displayed superior performance than conventional devices using poly­(3,4-ethylenedioxythiophene)/poly­(styrenesulfonate) sulfonic acid (PEDOT/PSS). The highest power conversion efficiency of the PSCs based on CuI layer reached 4.15% under the illumination of AM 1.5G, 100 mW/cm<sup>2</sup>. Furthermore, the pristine CuI layer could be applied in PSCs immediately, which shortened the production time of PSCs.