Efficient Inverted Organic Solar Cells Based on a Fullerene Derivative-Modified Transparent Cathode.

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Indium tin oxide (ITO) is a crucial transparent conductive material for organic solar cells (OSCs).
• ITO serves as the cathode in inverted OSCs, requiring modification with cathode buffer layers (CBLs) for optimal performance.
• Effective CBLs are essential for improving interfacial contact and charge transport in OSC devices.

Purpose of the Study:

• To investigate the efficacy of an amine group functionalized fullerene derivative (DMAPA-C60) as a CBL for ITO cathodes in inverted OSCs.
• To compare the performance of DMAPA-C60 modified ITO with traditional ZnO CBLs.
• To elucidate the mechanisms behind performance improvements attributed to the DMAPA-C60 CBL.

Main Methods:

• Fabrication of inverted OSCs utilizing PTB7 as the donor and PC71BM as the acceptor.
• Modification of ITO cathodes with DMAPA-C60 and ZnO as CBLs.
• Characterization of optical transmittance, nanoscale surface morphology, and device performance metrics (e.g., PCE).

Main Results:

• DMAPA-C60 exhibited comparable transmittance to ZnO CBLs.
• OSCs employing DMAPA-C60 demonstrated significantly enhanced power conversion efficiencies (PCEs) from 6.24% to 7.43% compared to ZnO counterparts.
• Nanoscale morphology revealed a plainer surface for DMAPA-C60-modified ITO, facilitating improved electron transport and collection.

Conclusions:

• DMAPA-C60 serves as an effective CBL for ITO cathodes in inverted OSCs.
• The improved performance is attributed to enhanced interfacial contact and superior electron transport and collection.
• DMAPA-C60 offers a promising alternative to conventional CBLs for boosting OSC device efficiency.