Toward Highly Efficient Inkjet-Printed Perovskite Solar Cells Fully Processed Under Ambient Conditions and at Low Temperature

Considering the recent advances in the fundamental understanding of perovskite devices as well as in the demonstration of larger stability under working conditions, specific attention has still to be paid for their processing for low-cost applications. Here, the successful demonstration of 10.7% efficient chlorine-doped methylammonium lead iodide (CH3NH3PbI3-xClx) solar cells based on a fully inkjet-printed processed under ambient conditions and at low temperature (<90 degrees C) is reported. A huge hysteresis is observed and the efficiency drops down to 6.4% for the forward scan. The Owens-Wendt-Rabel and Kaelble model is applied to investigate the impact of chloride, bromide, or diiodooctane on the perovskite ink wetting properties. A low surface energy of the substrate provokes dewetting during the perovskite printing. The use of chlorine or bromide tends to increase the wettability of the perovskite ink, improving the impregnation of the ink in porous materials. This work shows the critical importance of properly storing these substrates prior to active layer deposition, in order to produce homogenous layers by inkjet-printing. The successful printing of all inner layers, excluding bottom and top electrodes, in ambient atmosphere is an additional step toward their expected development at a larger scale by the printed electronic industry.