Efficient perovskite/silicon tandem with asymmetric self-assembly molecule

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Achieving uniform self-assembled monolayers on silicon is crucial for efficient perovskite/silicon tandem solar cells.
• Existing symmetric molecules face challenges with coverage and steric hindrance on textured substrates.

Purpose of the Study:

• To design and evaluate an asymmetric self-assembled monolayer (HTL201) as a hole-selective layer for perovskite/silicon tandem solar cells.
• To overcome limitations of current materials for improved solar cell performance.

Main Methods:

• Design of an asymmetric molecule (HTL201) with a carbazole core, anchoring group, and spacer.
• Application of HTL201 as a hole-selective layer on transparent conductive oxide recombination layers.
• Characterization of molecular coverage, coordination interaction, and energy-level alignment.

Main Results:

• HTL201 exhibits minimized steric hindrance and improved coverage compared to symmetric molecules.
• Strong coordination between HTL201 and perovskite films reduces non-radiative recombination.
• Optimized energy-level alignment and increased quasi-Fermi-level splitting lead to a voltage near 2V.

Conclusions:

• The asymmetric HTL201 molecule significantly enhances perovskite/silicon tandem solar cell performance.
• HTL201 enables a certified power conversion efficiency of 34.58% for silicon heterojunction solar cells.
• This work provides a pathway for developing advanced hole-selective layers for next-generation solar technologies.