Efficient ternary blend bulk heterojunction solar cells with tunable open-circuit voltage

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Bulk heterojunction (BHJ) organic solar cells are a promising renewable energy technology.
• Ternary blends, incorporating a third component, are being explored to enhance BHJ performance.
• Understanding the interplay of multiple acceptors is crucial for optimizing device efficiency.

Purpose of the Study:

• To investigate the potential of ternary blend BHJ photovoltaics for improving organic solar cell performance.
• To examine a model system using poly(3-hexylthiophene) (P3HT) as the donor and two fullerene acceptors (PC61BM and ICBA).

Main Methods:

• Fabrication of BHJ solar cells with a fixed P3HT:fullerene ratio (1:1).
• Systematic variation of the fullerene component composition (PC61BM:ICBA ratio).
• Characterization of photovoltaic device performance, including short-circuit current density (Jsc), fill factor (FF), and open-circuit voltage (Voc).

Main Results:

• Devices exhibited high Jsc and FF (>0.57) across all fullerene ratios.
• Voc was tunable, ranging from 0.61 V to 0.84 V, by adjusting the ICBA fraction.
• Voc in ternary blends is not limited by the lowest Voc of binary blends and can be varied independently of Jsc and FF.

Conclusions:

• Ternary blends offer an effective strategy for maximizing the JscVoc product in BHJ solar cells.
• This approach allows for efficiencies potentially exceeding theoretical limits of binary blends.
• Judicious selection of donor and acceptor components in ternary systems is key for high-performance, single-active-layer devices.