Interface Engineering with Co-Self-Assembled Monolayers for Improved Charge Extraction and Morphology in Organic...

Area of Science:

• Materials Science
• Organic Electronics
• Surface Chemistry

Background:

• Carbazole-based self-assembled monolayers (SAMs), like [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), are crucial hole-selective layers (HSLs) in organic photovoltaics (OPVs).
• Limitations of single-component SAMs, such as 2PACz, hinder further improvements in OPV device performance.
• Molecular modification of SAMs is a common strategy but introduces complexities.

Purpose of the Study:

• To introduce a coself-assembled monolayer (co-SAM) strategy using 2PACz and 4PDACB to overcome the limitations of single-component SAMs in OPVs.
• To optimize electrode work function, interfacial quality, and active layer morphology through co-SAM formation.
• To enhance the overall performance and power conversion efficiency (PCE) of organic photovoltaics.

Main Methods:

• Fabrication of coself-assembled monolayers (co-SAMs) by blending 2PACz and 4PDACB.
• Optimization of PM6:Y6-based organic photovoltaics (OPVs) utilizing the co-SAM strategy.
• Performance evaluation of co-SAM modified OPVs, including power conversion efficiency (PCE) measurements.

Main Results:

• The co-SAM strategy significantly improved OPV performance, achieving a PCE of 17.55% in PM6:Y6 devices, surpassing single-layer 2PACz (17.08%) and 4PDACB (16.13%) devices.
• Co-SAMs demonstrated effectiveness in ternary OPVs, reaching a maximum PCE of 18.69%.
• The co-SAM approach successfully balanced work function tuning, interfacial quality, and active layer morphology.

Conclusions:

• Coself-assembled monolayers offer a promising approach to enhance OPV performance by synergistically combining different SAM components.
• Surface engineering via co-SAMs plays a critical role in controlling film morphology and improving device efficiency.
• This strategy provides valuable insights for the development of next-generation high-performance organic photovoltaics.