Solid-state-ligand-exchange free quantum dot ink-based solar cells with an efficiency of 10.9%

While colloidal quantum dot based solar cells (CQDSCs) have recently achieved power conversion efficiencies (PCE) up to 11.3%, the CQD active layers are fabricated almost exclusively by a combined process of in situ solid-state ligand exchange (SSE) with multiple layer-by-layer (LbL) deposition, which has been a major obstacle to high-throughput processing. In this work, we developed, for the first time, high-efficiency CQDSCs without using either the SSE or LbL technique. The fabrication of n-p quantum dot junctions by SSE-free direct coating was achieved using n-type CQD ink and p-type CQD ink. The ink based devices achieved a PCE of approximate to 11%, which is comparable to the current state-of-the-art performance. The CQD inks enabled, for the first time, use of the doctor-blade coating method for device fabrication. Notably, the PCE of the bladed CQDSCs was remarkably high, at >10%, which suggests its potential use in other industrially friendly processes.