Guanidyl-Engineered SAMs with Electrostatic-Coordination Synergy for High-Efficiency Tandem-Compatible Perovskite...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Wide-bandgap inverted perovskite solar cells (PSCs) show promise for stability and tandem applications.
• Challenges include self-assembled monolayer (SAM) inhomogeneity and poor passivation of interface defects.

Purpose of the Study:

• To improve the stability and efficiency of wide-bandgap inverted PSCs.
• To address SAM inhomogeneity and interface defect issues using a novel additive.

Main Methods:

• Incorporation of polyhexamethylene guanidine hydrochloride (PHMG) as an additive to 4-(7H-dibenzo[c,g]carbazole-7-yl) phosphonic acid (4PADCB) SAMs.
• Investigating the synergistic electrostatic-coordination effects between PHMG, 4PADCB, and perovskite.
• Fabrication and characterization of optimized PSCs and perovskite/silicon tandem solar cells.

Main Results:

• Optimized 1.68 eV-bandgap PSCs achieved a record power conversion efficiency (PCE) of 23.62%.
• The devices demonstrated excellent stability, retaining over 95% efficiency after 1300 hours of aging at 85°C.
• Integrated PSCs achieved record PCEs of 32.49% (laminated tandem) and 32.25% (1 cm² monolithic tandem).

Conclusions:

• PHMG additive effectively suppresses SAM aggregation and reduces interfacial defects in PSCs.
• The synergistic effects enhance perovskite crystallization, reduce defect densities, and improve energy-level alignment.
• This approach significantly advances PSC and tandem solar cell performance and stability.