Extending Exciton Diffusion Length via an Organic-Metal Platinum Complex Additive for High-Performance Thick-Film...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Long exciton diffusion length (L_D) is crucial for efficient organic solar cells (OSCs), particularly in thick films.
• Limited L_D restricts performance improvements as film thickness increases, hindering exciton dissociation and charge transport.
• Reducing charge recombination and energy disorder are key challenges in advancing OSC technology.

Purpose of the Study:

• To investigate the effect of an organic-metal platinum complex (TTz-Pt) as a solid additive in OSCs.
• To enhance exciton diffusion length (L_D) and improve the performance of thick-film organic solar cells.
• To explore a universal method for boosting OSC efficiency through material additive engineering.

Main Methods:

• Synthesis of an organic-metal platinum complex, TTz-Pt.
• Incorporation of TTz-Pt as a solid additive into the D18-Cl:L8-BO organic solar cell system.
• Characterization of blend crystallinity, energy disorder, trap density, non-radiative recombination, and exciton binding energy.

Main Results:

• TTz-Pt addition enhanced blend crystallinity, reduced energy disorder and trap density, and decreased non-radiative recombination and exciton binding energy.
• The TTz-Pt-treated D18:L8-BO:IDIC device (100 nm) achieved a champion power conversion efficiency (PCE) of 20.12%.
• A record-breaking PCE of 18.84% was achieved for a 300 nm thick active layer, demonstrating effectiveness in thick-film devices.

Conclusions:

• TTz-Pt effectively prolongs exciton diffusion length (L_D), facilitating exciton dissociation and charge transport while inhibiting recombination.
• The organic-metal platinum complex provides a simple and universal approach to significantly improve OSC performance, especially for thick films.
• This strategy offers a promising pathway for developing next-generation, highly efficient organic solar cells.