Effect of Anode Interfacial Modification by Self-Assembled Monolayers on the Organic Solar Cell Performance

Area of Science:

• Materials Science
• Organic Electronics
• Renewable Energy

Background:

• Organic solar cells (OSCs) require efficient charge transport layers for optimal performance.
• Interfacial engineering of electrodes, such as Indium Tin Oxide (ITO), is crucial for improving OSC device efficiency.
• Self-assembled monolayers (SAMs) offer a versatile approach to modify electrode work functions and surface properties.

Purpose of the Study:

• To synthesize novel SAM-based benzoic acid derivatives for use as interlayers in OSCs.
• To investigate the impact of these SAM interlayers on the work function and wetting properties of ITO electrodes.
• To evaluate the performance enhancement of OSC devices incorporating these SAM interlayers.

Main Methods:

• Synthesis of benzoic acid derivatives: 4-[5'-phenyl-2,2'-bitien-5-yl] benzoic acid (ZE-Ph), 4-[5'-(4-fluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-1F), and 4-[5'-(3,5-difluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-2F).
• Fabrication of organic solar cells (OSCs) using a poly-3 hexylthiophene (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PC61BM) blend with SAMs as interlayers between ITO and MoO3.
• Device characterization using Kelvin probe force microscopy, cyclic voltammetry, contact angle measurements, and I-V measurements.

Main Results:

• SAM interlayers successfully tuned the work function and surface wetting of ITO electrodes.
• Power conversion efficiency (PCE) increased from 1.93% (control) to 2.20% (ZE-Ph) and 2.22% (ZE-1F).
• Short-circuit current density (Jsc) and open-circuit voltage (Voc) were significantly improved, indicating enhanced hole transport.

Conclusions:

• Self-assembled monolayers serve as an effective interlayer strategy to enhance OSC performance.
• The synthesized benzoic acid derivatives (ZE-Ph, ZE-1F) demonstrably improve charge transport and device efficiency.
• Interfacial modification using SAMs is a promising route for developing next-generation organic solar cells.