Tuning the buried interface with d-sorbitol-modified mixed SAMs for high-efficiency inverted perovskite solar cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) face challenges in efficiency and stability due to non-radiative recombination and interfacial losses at the transparent conducting oxide/perovskite interface.
• Existing methods struggle to effectively address these buried interface issues, limiting overall device performance.

Purpose of the Study:

• To develop a novel surface modification strategy to mitigate interfacial losses in PSCs.
• To improve the efficiency, stability, and reduce hysteresis in inverted (p-i-n) perovskite solar cells.

Main Methods:

• Fabrication of a hole-selective contact using a mixed 2PACz/MeO-2PACz self-assembled monolayer (SAM) on a high-haze FTO substrate.
• Post-deposition modification of the buried interface with d-sorbitol (DS), a polyol.
• Characterization using X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), and device performance testing.

Main Results:

• DS treatment preserved perovskite crystal structure and promoted smoother crystallization.
• DS enhanced surface wettability and reduced non-radiative recombination, evidenced by increased PL intensity and prolonged decay times.
• Modified devices showed increased short-circuit current (Jsc) and open-circuit voltage (Voc), boosting power conversion efficiency (PCE) from 14.1% to 16.1% and reducing hysteresis.
• DS-treated devices demonstrated improved shelf-storage stability, retaining 81.7% PCE after 8 days compared to 42.2% for the reference.

Conclusions:

• Polyol-assisted mixed-SAM engineering offers a simple, solution-processable route to effectively mitigate slow interfacial losses in PSCs.
• The d-sorbitol modification significantly enhances both the performance and long-term stability of inverted (p-i-n) perovskite solar cells.