Highly Efficient and Stable Perovskite Solar Cells Enabled by Low-Cost Industrial Organic Pigment Coating.

Surface passivation of perovskite solar cells (PSCs) using a low-cost industrial organic pigment quinacridone (QA) is presented. The procedure involves solution processing a soluble derivative of QA, N,N-bis(tert-butyloxycarbonyl)-quinacridone (TBOC-QA), followed by thermal annealing to convert TBOC-QA into insoluble QA. With halide perovskite thin films coated by QA, PSCs based on methylammonium lead iodide (MAPbI3 ) showed significantly improved performance with remarkable stability. A PCE of 21.1 % was achieved, which is much higher than 18.9 % recorded for the unmodified devices. The QA coating with exceptional insolubility and hydrophobicity also led to greatly enhanced contact angle from 35.6° for the pristine MAPbI3 thin films to 77.2° for QA coated MAPbI3 thin films. The stability of QA passivated MAPbI3 perovskite thin films and PSCs were significantly enhanced, retaining about 90 % of the initial efficiencies after more than 1000 hours storage under ambient conditions.