Constructing molecular bridge for high-efficiency and stable perovskite solar cells based on P3HT

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Poly(3-hexylthiophene) (P3HT) is a key hole transport material (HTM) for perovskite solar cells (PSCs).
• Poor interfacial contact and recombination at the P3HT/perovskite interface limit device performance and efficiency.
• Developing strategies to improve interfacial properties is crucial for high-efficiency and stable PSCs.

Purpose of the Study:

• To design and synthesize a molecular bridge (MDN) to enhance the performance of P3HT as an HTM in PSCs.
• To improve charge transport and reduce recombination at the P3HT/perovskite interface.
• To enhance the overall power conversion efficiency (PCE) and long-term stability of PSCs.

Main Methods:

• Synthesis of 2-((7-(4-(bis(4-methoxyphenyl)amino)phenyl)-10-(2-(2-ethoxyethoxy)ethyl)-10H-phenoxazin-3-yl)methylene)malononitrile (MDN).
• Incorporation of MDN into P3HT to create MDN-doped P3HT (M-P3HT) as the HTM.
• Fabrication and characterization of PSCs using M-P3HT and pristine P3HT as HTMs.
• Testing device performance, including PCE, and long-term stability under various environmental conditions and operational stress.

Main Results:

• MDN acts as a molecular bridge, facilitating π-π stacking with P3HT and anchoring to the perovskite surface via its malononitrile group.
• MDN effectively passivates defects and significantly reduces recombination at the interface.
• PSCs utilizing M-P3HT achieved a PCE of 22.87%, outperforming those with pristine P3HT.
• Un-encapsulated devices demonstrated enhanced stability, retaining 92% of initial efficiency after two months at 75% RH followed by one month at 85% RH, and showed no PCE degradation after 500 hours of continuous operation.

Conclusions:

• The designed molecular bridge (MDN) effectively enhances the interfacial properties of P3HT in PSCs.
• MDN-based HTMs lead to higher power conversion efficiencies and improved operational and environmental stability in perovskite solar cells.
• This strategy offers a promising approach for developing next-generation, stable, and efficient perovskite solar cells.