Tuning the Energy Level Offset between Donor and Acceptor with Ferroelectric Dipole Layers for Increased Efficiency in Bilayer Organic Photovoltaic Cells

摘要

Organic photovoltaic (OPV) technology is one of the most attractive candidates for solving future energy problems due to its advantages of light weight, flexibility, low cost of materials and large scale production. The highest power conversion efficiency (PCE) of OPV devices has been increased to 8-9%.Despite significant progress, further increasing the PCE to over 15% is needed for OPV to compete with silicon solar cells and other thin-film photovoltaic technologies for commercialization. The thermodynamic efficiency limit of OPV devices is 22-27%, so there is much space for improvement. One grand challenge facing OPV device efficiency improvement is the significant energy loss incurred during the charge transfer from the donor to the acceptor, because of the energy level mismatch and the inefficient separation as well as the inefficient extraction of the bound electron-hole pairs, causing a large photovoltage loss in most OPV devices.For example, the open circuit voltage