Solution-Processed Small-Molecule Bulk Heterojunctions: Leakage Currents and the Dewetting Issue for Inverted Solar...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Substrate properties critically influence organic photovoltaic (OPV) device performance.
• Solution-processed small molecule organic solar cells (OSCs) are a key area of research.

Purpose of the Study:

• To investigate the effect of substrate physicochemical properties on OPV performance.
• To identify strategies for improving OPV efficiency despite substrate roughness.

Main Methods:

• Tested ITO substrates coated with PSS, ZnO sol-gel, and ZnO nanoparticles.
• Analyzed active layer film formation and dewetting points.
• Incorporated polystyrene (PS) into the active layer to mitigate roughness effects.

Main Results:

• ZnO nanoparticle substrates exhibited low PV performance due to active layer dewetting caused by high roughness.
• Adding PS to the active layer improved film quality and reduced dark currents.
• High-efficiency OPV devices were achieved using the PS-modified active layer, even on rougher substrates.

Conclusions:

• Substrate roughness is a critical factor in achieving high-performance organic solar cells.
• Polystyrene incorporation is an effective strategy to overcome performance losses associated with rough substrates.
• This method enables high-efficiency OPV fabrication on diverse substrate types.