An unconventional blade coating for low-cost fabrication of PCDTBT: PC70BM polymer and CH3NH3PbIxCl3-x perovskite solar cells

Abstract

A low-cost and unconventional blade coating technique, called convective deposition, has been introduced for PCDTBT:PC70BM polymer and CH3NH3PbIxCl3-x perovskite solar cell fabrication. With the new technique, only 10–20 microliter droplets per one square inch substrate were used to deposit hole transporting material, as well as photoactive and electron transporting materials, sequentially to create a p-i-n structure solar cell. Thin film deposition and solar cell fabrication from the standard spin coating and the convective deposition were compared. Smaller and better distribution of PC70BM domain in the PCDTBT:PC70BM film was observed in the film prepared by the convective deposition. Unlike the conventional doctor-blade coating or the spin coating, the film thickness can simply be adjusted by the convective deposition speed. The highest averaged power conversion efficiency (PCE) of 6.34% was obtained from the polymer solar cell prepared by the convective deposition at the coating speed of 750 μm/s compared to 5.60% PCE from the spin coating at the speed of 2500 rpm. For perovskite solar cell, a heating stage was used during the convective deposition of perovskite ink, 10.61% PCE was achieved with the stage temperature of 70 °C and the 2500 μm/s deposition speed. Layer-by-layer deposition with the convective deposition used in this study offers benefits over the standard spin coating by reducing amount of material consumption in the fabrication process and being suitable for low-cost fabrication of other solution-based optoelectronic devices.