CuI as versatile hole-selective contact for organic solar cell based on anthracene-containing PPE–PPV

An important issue in construction of organic photovoltaic cells concerns the selective contacts. Here, especially the modification of the hole-extraction is challenging, as energy levels have to match the polymer's highest occupied molecular orbital (HOMO). We took the view to the mutual anode interface and we sought for a solution-based alternative for commonly used PEDOT:PSS – with an eye on improving the hole-extraction with an inorganic interlayer. We present copper iodide (CuI) as a versatile inorganic p-type semiconductor that meets the requirements for enhanced charge extraction in donor polymers. We applied two types of anthracene-containing PPE–PPV block–copolymers that recently gained attention as efficient active absorbers in bulk heterojunction photovoltaic cells. We report on the advantages using CuI as hole-selective contact and show an improvement of the power conversion efficiency in polymer-based solar cells. [Display omitted] •CuI replaces PEDOT:PSS as hole-selective contact.•Solution-processed layers of CuI are investigated by spectroscopic ellipsometry.•CuI thin-layers improve the hole-selectivity in bulk-heterojunction solar cells.•Thin CuI films are promoted as transparent hole-selective contact layer.