Ruthenium Chloride as a Versatile and Stable Hole Transport Material for Organic Solar Cells and Photocathodes

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) require efficient hole transport layers (HTLs) for optimal performance and stability.
• Existing HTLs often face challenges in achieving a balance between charge extraction, energy-level alignment, and long-term durability.

Purpose of the Study:

• To introduce ruthenium chloride (RuCl3) as a novel and robust HTL for organic optoelectronic devices.
• To investigate the impact of annealing temperature on RuCl3's electrochemical properties and device performance.
• To evaluate the stability and efficiency of OSCs utilizing RuCl3 as an HTL.

Main Methods:

• Fabrication of OSCs with RuCl3 as the HTL.
• Optimization of RuCl3 film processing via annealing temperature control (specifically at 100 °C).
• Electrochemical characterization of RuCl3 films and device performance testing under simulated solar illumination and thermal stress.

Main Results:

• RuCl3 films processed at 100 °C demonstrated a suitable work function for efficient hole extraction from organic photoactive materials.
• Devices achieved a power conversion efficiency (PCE) of 18.02% with low leakage current and reduced interfacial charge transfer resistance.
• RuCl3 exhibited superior operational stability, retaining 80.3% of initial PCE after 1724 hours of 1-sun illumination and 73.7% after 692 hours at 85 °C.
• RuCl3-based photocathodes showed a photocurrent of 14.9 mA cm⁻² and remarkable resilience to electrochemical stress.

Conclusions:

• Ruthenium chloride (RuCl3) is a highly effective and stable HTL for organic solar cells and other optoelectronic applications.
• The optimized RuCl3 HTL significantly enhances device efficiency and long-term operational durability.
• RuCl3 presents a promising, robust alternative to conventional HTLs, paving the way for more reliable organic electronic devices.