Defect-Passivating and Dense Indolocarbazole-Based Self-Assembled Monolayers for Efficient Inverted Perovskite Solar...

Area of Science:

• Materials Science
• Photovoltaics
• Organic Electronics

Background:

• Self-assembled monolayers (SAMs) are crucial for NiO_x-based inverted perovskite solar cells (PSCs).
• Limitations of current SAMs include poor wettability, low surface coverage, and inadequate defect passivation, hindering PSC performance and stability.
• Developing novel SAMs is essential for advancing PSC technology.

Purpose of the Study:

• To design and synthesize novel indolocarbazole-based SAMs for enhanced PSC performance.
• To investigate the impact of nitrogen positions and anchoring group number on SAM properties and device characteristics.
• To evaluate the efficiency and stability of PSCs utilizing the developed SAMs.

Main Methods:

• Synthesis of four indolocarbazole-based SAMs: D3PAICz-1, M3PAICz-1, D3PAICz-2, and M3PAICz-2.
• Systematic investigation of SAM properties, including surface wettability, film uniformity, and energy level alignment.
• Fabrication and characterization of PSCs with varying bandgaps (1.55 eV and 1.68 eV) using the synthesized SAMs.
• Assessment of device power conversion efficiency (PCE) and air stability.

Main Results:

• Monophosphonate-anchored M3PAICz-1 exhibited superior surface wettability, compactness, film uniformity, and defect passivation compared to other SAMs.
• PSCs with a 1.55 eV bandgap using M3PAICz-1 achieved a record PCE of 26.12% and excellent air stability.
• M3PAICz-1 also enabled a 1.68 eV wide-bandgap PSC to reach an impressive PCE of 22.19%, demonstrating its versatility as a hole transport layer (HTL).

Conclusions:

• Indolocarbazole-based SAMs, particularly M3PAICz-1, offer significant improvements in PSC efficiency and stability.
• Molecular design of SAMs, considering nitrogen positions and anchoring groups, is critical for optimizing PSC performance.
• The developed SAMs provide a promising pathway for the practical application of high-performance perovskite solar cells.