Electrostatically Enhanced Buried Interface Binding of Self-Assembled Monolayers for Efficient And Stable Inverted...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Inverted p-i-n perovskite solar cells (PSCs) show superior performance compared to n-i-p structures.
• Self-assembled monolayers (SAMs) are crucial for hole transport layers in PSCs.
• Carbazole-based phosphonic acids, commonly used SAMs, exhibit weak binding with transparent conducting oxides (TCOs) and perovskite, limiting device stability.

Purpose of the Study:

• To enhance interfacial binding in PSCs by modifying SAMs.
• To improve the stability and efficiency of perovskite solar cells through optimized interfacial adhesion.

Main Methods:

• Designed and synthesized a novel donor-acceptor SAM molecule, PAFTB (4-(7-(4-(bis(4-methoxyphenyl)amino)-2,5-difluorophenyl)benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid).
• Incorporated tailored functional groups and increased the dipole moment of SAMs to improve chemical anchoring and electrostatic interactions.
• Investigated the binding strength and thermal stability of the modified SAMs compared to traditional ones like 2PACz ([2-(9H-carbazol-9-yl)ethyl]phosphonic acid).

Main Results:

• PAFTB demonstrated a 2.8-fold increase in total interfacial adhesion compared to 2PACz.
• The enhanced adhesion led to improved thermal stability of the hole transport layer.
• PSCs fabricated with PAFTB achieved a certified power conversion efficiency of 24.9%.

Conclusions:

• The developed PAFTB molecule effectively enhances interfacial binding and stability in PSCs.
• Optimized interfacial engineering is key to achieving high-performance and durable perovskite solar cells.
• The study presents a promising strategy for advancing PSC technology through molecular design.