Enhanced Photovoltaic Performance of Ternary Small Molecule/Polymer Bulk Heterojunction Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic photovoltaics (OPVs) are promising for renewable energy.
• Small-molecule OPVs face challenges in light absorption and charge transport.
• Ternary blends offer a strategy to overcome these limitations.

Purpose of the Study:

• To enhance the performance of small-molecule organic photovoltaics (OPVs).
• To investigate the effect of a ternary blend including a polymer donor on OPV efficiency.
• To understand the role of polymer donors in optimizing active layer morphology and charge transport.

Main Methods:

• Fabrication of organic photovoltaics (OPVs) using a ternary blend active layer.
• Compositional optimization of the ternary blend: small-molecule donor (DTS(FBTTh2)2), polymer donor (PBDTTT-EFT), and fullerene acceptor (PC71BM).
• Characterization of power conversion efficiency (PCE) and analysis of underlying mechanisms.

Main Results:

• Achieved a significant increase in power conversion efficiency (PCE) from 7.99% to 9.08%.
• The polymer donor (PBDTTT-EFT) broadened the light absorption spectrum.
• Enhanced charge transport pathways and optimized nanomorphology of the bulk heterojunction films were observed.

Conclusions:

• Semiconducting polymer donors effectively control light absorption, charge transport, and exciton dissociation in OPVs.
• Optimizing morphology and crystallinity through polymer donors is key to improving OPV performance.
• This ternary blend approach offers a viable strategy for advancing organic photovoltaic devices.