Selenophene-Based Hole-Transporting Materials for Perovskite Solar Cells

Area of Science:

• Materials Science
• Organic Chemistry
• Photovoltaics

Background:

• Donor-π-bridge-donor (D-π-D) architectures are crucial for hole-transporting materials (HTMs) in perovskite solar cells (PSCs).
• Triphenylamine (TPA) and thiophene units are common building blocks in high-performance HTMs.
• Developing novel HTMs with tailored electronic and thermal properties is essential for advancing PSC technology.

Purpose of the Study:

• To synthesize and characterize novel D-π-D hole-transporting materials (HTMs) incorporating selenium.
• To investigate the optoelectronic and thermal properties of these new selenium-based HTMs.
• To evaluate the performance of these HTMs in mesoporous perovskite solar cells (PSCs).

Main Methods:

• Synthesis of two novel D-π-D HTMs featuring p-methoxytriphenylamine (TPA) donor units linked by a 3,4-dimethoxyselenophene spacer.
• Characterization of optoelectronic and thermal properties using experimental techniques.
• Density functional theory (DFT) calculations for theoretical property assessment.
• Fabrication and testing of mesoporous PSCs utilizing the synthesized HTMs and a specific triple-cation perovskite composition.

Main Results:

• Successful synthesis of two novel selenium-containing D-π-D HTMs.
• Experimental and DFT studies revealed the optoelectronic and thermal characteristics of the new materials.
• PSCs incorporating the novel HTMs achieved power conversion efficiencies up to 13.4%, lower than the benchmark spiro-OMeTAD (17.8%).

Conclusions:

• The synthesized selenium-based HTMs exhibit promising optoelectronic properties but are limited by poor film-forming ability.
• Structural defects, such as pinholes, arising from inadequate film formation negatively impact photovoltaic performance.
• Further material design focusing on improved film morphology is necessary to enhance the efficiency of PSCs employing these novel HTMs.