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 (MAPbI(3)) 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 degrees for the pristine MAPbI(3) thin films to 77.2 degrees for QA coated MAPbI(3) thin films. The stability of QA passivated MAPbI(3) perovskite thin films and PSCs were significantly enhanced, retaining about 90 % of the initial efficiencies after more than 1000 hours storage under ambient conditions.