Well-defined star-shaped conjugated macroelectrolytes as efficient electron-collecting interlayer for inverted...

Area of Science:

• Organic electronics
• Materials science
• Photovoltaics

Background:

• Inverted polymer solar cells require efficient electron-collecting cathode interlayers.
• Existing buffer layers like sol-gel ZnO and Ca/Al cathodes have limitations in performance and stability.

Purpose of the Study:

• To design, synthesize, and evaluate novel star-shaped conjugated macroelectrolytes (TrNBr and TrOH) as cathode interlayers.
• To investigate the effect of these interlayers on work function modulation and device performance.
• To compare the performance and stability of inverted solar cells using TrNBr and TrOH with conventional devices.

Main Methods:

• Synthesis of star-shaped monodisperse conjugated macroelectrolytes TrNBr and TrOH.
• Fabrication of inverted polymer solar cells with TrNBr and TrOH as cathode interlayers.
• Systematic study of surface properties and work function modulation.
• Optimization of interlayer thickness and performance evaluation.

Main Results:

• Optimized TrNBr (2.4 nm) and TrOH (8.7 nm) interlayers significantly improved performance.
• Power conversion efficiencies reached 4.88% for TrNBr and 4.74% for TrOH, outperforming conventional devices (3.94%) and ZnO-buffered devices (4.21%).
• Devices with TrNBr and TrOH interlayers exhibited enhanced operational stability.

Conclusions:

• Star-shaped conjugated macroelectrolytes TrNBr and TrOH are effective electron-collecting interlayers for inverted polymer solar cells.
• Thickness optimization is crucial for achieving high power conversion efficiency.
• These novel interlayers offer a promising alternative for improving both performance and stability in organic photovoltaics.