Multifunctional Biomolecules Bridging a Buried Interface for Efficient Perovskite Solar Cells.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Charged defects at the SnO2/perovskite interface in perovskite solar cells (PSCs) cause nonradiative recombination and poor energy level alignment.
• Interface engineering is crucial for managing these charged defects and improving PSC performance.

Purpose of the Study:

• To introduce nicotinamide adenine dinucleotide (NAD) molecules to bridge the SnO2/perovskite interface.
• To simultaneously eliminate both positively and negatively charged defects.
• To enhance the performance of PSCs through interface modification.

Main Methods:

• Utilized NAD molecules with multiple active groups (─P=O, ─P-O, ─NH2) for interface bridging.
• Investigated the role of NAD's functional groups in fixing uncoordinated Pb2+ and filling oxygen vacancies (V_O).
• Analyzed the formation of hydrogen bonds between NAD's ─NH2 groups and PbI2.
• Fabricated PSCs with an ITO/SnO2/NAD/Cs0.15FA0.75MA0.1PbI3/Spiro-OMeTAD/Ag structure.

Main Results:

• NAD molecules effectively eliminated positively charged defects by interacting with Pb2+ and V_O.
• NAD's ─NH2 groups reduced negatively charged defects through hydrogen bonding with PbI2.
• NAD facilitated improved perovskite crystallization and accelerated electronic transfer.
• Achieved favorable energy band alignment between SnO2 and perovskite layers.
• PSC power conversion efficiency increased from 20.49% to 23.18% with an open-circuit voltage of 1.175 V.

Conclusions:

• Multifunctional molecular bridges like NAD are effective for interface engineering in PSCs.
• Simultaneous elimination of charged defects and regulation of energy level alignment significantly boost PSC performance.
• This approach offers a promising strategy for developing high-efficiency perovskite solar cells.