Highly Efficient and Stable Organic Solar Cells via Interface Engineering with a Nanostructured ITR-GO/PFN Bilayer...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Organic solar cells (OSCs) require efficient charge transport layers for optimal performance.
• Developing stable and high-performing cathode interlayers (CILs) is crucial for advancing OSC technology.
• Existing CILs often face challenges in achieving both high electronic quality and cost-effective fabrication.

Purpose of the Study:

• To develop an innovative bilayer CIL composed of in situ thermal reduced graphene oxide (ITR-GO) and poly[(9,9-bis(3'-(N,N-dimethylamion)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl) fluorene] (PFN).
• To investigate the CIL's ability to modulate the active layer-electrode interface morphology and reduce electrode work function.
• To enhance the power conversion efficiency (PCE) and long-term stability of inverted OSCs.

Main Methods:

• Fabrication of a bilayer ITR-GO/PFN CIL using a facile spray-coating method with in situ thermal reduction.
• Characterization of the CIL's nanostructure and electronic properties.
• Integration of the CIL into Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl} (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)-based OSCs.
• Evaluation of device performance, including PCE and long-term stability, compared to pristine devices.

Main Results:

• The ITR-GO/PFN CIL demonstrated high electronic quality and effectively modulated the interface morphology.
• Spray-coating with facile in situ thermal reduction provided an efficient fabrication method.
• The CIL exhibited improved charge transport efficiency and reduced charge recombination.
• The PCE of the OSCs significantly increased from 6.47% to 8.34%.
• Long-term device stability was notably improved compared to devices without the ITR-GO/PFN CIL.

Conclusions:

• The bilayer ITR-GO/PFN CIL is a promising strategy for fabricating high-efficiency and stable inverted OSCs.
• The use of ITR-GO as a template offers a novel approach to optimize CIL morphology and electronic properties.
• Water-soluble conjugated polymer electrolytes like PFN, combined with ITR-GO, present a viable pathway for next-generation OSCs.