Relationship Between the Diode Ideality Factor and the Carrier Recombination Resistance in Organic Solar Cells

Organic solar cells are about to become a potential competitor to silicon solar cells. It is vital to understand the carrier recombination mechanism of organic solar cells to improve the device performance further. The diode ideality factor and carrier recombination resistance are the two commonly used parameters to describe the nongeminate, also called trap-assisted, recombination in solar cells. Herein, we demonstrated the relationship between these two parameters and derived an equation that can be used as a new method to estimate the carrier recombination resistance in organic solar cells. PBDB-T:ITIC-based nonfullerene organic solar cells, and PTB7:PC71BM and PffBT4T-2OD:PC71BM-based fullerene organic solar cells were fabricated to provide experimental proofs for our demonstration. A comparative study has been done between the fresh and aged PBDB-T:ITIC-based devices to further analyze the relationship between the carrier recombination resistance and the diode ideality factor.