Efficient Cathode Buffer Material Based on Dibenzothiophene-S,S-dioxide for Both Conventional and Inverted Organic...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) require efficient charge transport and collection at electrode interfaces.
• Developing effective cathode buffer materials (CBMs) is crucial for enhancing OSC performance and stability.
• Existing CBMs often face limitations in work function modulation and interfacial compatibility.

Purpose of the Study:

• To introduce and evaluate a novel conjugated molecule, PBSON, as a high-performance CBM for OSCs.
• To investigate the interfacial properties and charge transport characteristics of PBSON at cathode interfaces.
• To demonstrate the efficacy of PBSON in improving the power conversion efficiencies (PCEs) of both conventional and inverted OSCs.

Main Methods:

• Synthesis and characterization of the novel conjugated molecule PBSON.
• Fabrication and testing of organic solar cells incorporating PBSON as a CBM.
• Utilizing scanning Kelvin probe microscopy and theoretical calculations to analyze PBSON-cathode interactions.
• Performing electron-only device characterization to assess electron transport properties.

Main Results:

• PBSON exhibits a deep highest occupied molecular orbital (HOMO) level (-6.01 eV) suitable for hole blocking.
• PBSON possesses a wide energy bandgap (3.17 eV) ensuring high optical transmittance.
• PBSON effectively modulates cathode work functions, promoting Ohmic contacts and improving electron collection.
• PBSON-based OSCs showed significant PCE enhancements, up to 58.2% for conventional and 56.4% for inverted devices with the PTB7:PC71BM system.

Conclusions:

• PBSON is a highly effective CBM for both conventional and inverted OSC architectures.
• The unique electronic and interfacial properties of PBSON lead to substantial improvements in OSC performance.
• PBSON demonstrates potential for widespread application in high-efficiency organic solar cells.