Materials and Devices for Emerging Solar Cells

Colloidal quantum dot (CQD) based solar cell devices have emerged as one of the most promising types of solar cells owing to their easy bandgap tunability and solution processability. Recently, the power conversion efficiency (PCE) of the devices has been expanded to >11% by the development of high-quality CQD materials and device architectures. In this talk, the strategical approaches for materials development and device optimization to improve the performance of CQD solar cells (CQDSCs) are presented. In terms of materials development, the control of PbS-CQDs trap states are investigated through surface passivation using various ligands. The reduction of trap states of CQDs enhanced the charge carrier mobility and trap-assisted charge recombination improving the device PCE. Modification of the interfaces between CQD and charge accepting layer interfaces significantly influenced the charge transport and recombination in CQDSCs. Several different surface manipulation methods and their effects on charge recombination are discussed. The reduction of interfacial charge recombination further improved the open circuit voltage and fill factor of devices. We also developed CQD ink materials to achieve versatility in device fabrication engineering. The pre-exchanged CQD inks realized the fabrication of device without multiple depositions. Consequently, high efficiency CQDSCs with PCE of ~11% with decent air stability was achieved.