n-Doping of photoactive layer in binary organic solar cells realizes over 18.3% efficiency

Electronic doping of conjugated semiconductor plays a critical role in the fabrication of high efficiency organic optoelectronic devices. Here, we report an organic solar cell (OSC) by doping n-type DMBI-BDZC into one host binary bulk heterojunction (BHJ) photoactive layer comprised of a polymer donor PM6 and a nonfullerene acceptor Y6. The resulting champion device yields a significantly improved power conversion efficiency from 17.17% to 18.33% with an impressive fill factor of 80.20%. It is found that the electrically doped photoactive layer exhibits enhanced and balanced charge carrier mobilities, more effective exciton dissociation, longer carrier lifetime, and suppressed charge recombination with smaller energy loss. The dopant molecule DMBIBDZC also act as a surface morphology modifier of the photoactive layer with enhanced charge transport. This work demonstrates that manipulation of charge transport via adding a low concentration dopant into photoactive layer is a promising approach for further improvement of BHJ OSC performance.

Automated summary

In this study, an organic solar cell was developed with improved power conversion efficiency by doping DMBI-BDZC into the photoactive layer. The doped layer exhibited enhanced carrier mobilities, effective exciton dissociation, longer carrier lifetime, and suppressed charge recombination.