Asymmetric Conjugated Molecule Co-Deposition for High-Performance HTL-Free Carbon-Based Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Planar hole-transport-layer (HTL)-free carbon-based perovskite solar cells (C-PSCs) offer stability and cost-effectiveness.
• Limited power conversion efficiency (PCE) in HTL-free C-PSCs is due to interfacial nonradiative recombination and poor charge extraction.

Purpose of the Study:

• To design a novel molecule, 2BCz-BD, to overcome efficiency limitations in HTL-free C-PSCs.
• To enhance perovskite solar cell performance through improved crystallization, defect passivation, and charge extraction.

Main Methods:

• Designed an asymmetric D-A-D'-A' conjugated molecule (2BCz-BD).
• Utilized a co-deposition strategy, incorporating 2BCz-BD into the perovskite precursor solution.
• Investigated the molecule's coordination ability, semiconducting properties, and dipole moment.

Main Results:

• 2BCz-BD regulated perovskite crystallization and passivated surface defects, suppressing nonradiative recombination.
• Optimized energy-level alignment enhanced charge extraction.
• Achieved PCEs of 23.24% (small-area) and 22.09% (large-area).
• Unencapsulated devices retained >90.4% PCE after 3100 hours.

Conclusions:

• The 2BCz-BD molecule effectively enhances the performance and stability of HTL-free C-PSCs.
• Co-deposition strategy with 2BCz-BD enables high-quality perovskite film and electrode fabrication.
• Demonstrated a viable pathway for developing efficient and durable carbon-based perovskite solar cells.