An Inkjet-Printed Electron Transport Layer for Large-Area Perovskite Solar Cells Using a Commercial Inkjet Print Head

Abstract

The production of perovskite solar cells (PSCs) is moving beyond spin coating. Among various methods for fabricating large-area PSCs, inkjet printing is emerging as a promising alternative due to its low material waste and high precision. This work reports a method for inkjet printing an electron transport layer for PSCs using an industrial inkjet head capable of printing large areas. By analyzing the physical properties of the ink (Ohnesorge number) and optimizing the waveform, stable single-drop formation was achieved, enabling reliable ink ejection of the DI-water-based SnO₂ ink. The printed film was post-treated at an optimal drying temperature to successfully suppress the coffee ring effect and banding defects caused by swath, leading to a uniform SnO₂film. As the DPI increased, it was confirmed that the film surface became flatter and the density increased. The surface-enhanced electron transport layer (ETL) induced uniform nucleation and crystal growth in the upper perovskite layer, ultimately achieving a significant improvement in the device's photovoltaic performance. With high-DPI Inkjet printing, a device with power conversion efficiency (PCE) of 17.42 % is achieved.