Heterojunction Organic Solar Cells with Efficient Charge Mobility and Separation Capabilities Studied by DFT

Area of Science:

• Materials Science
• Physical Chemistry
• Organic Electronics

Background:

• Organic solar cells (OSCs) efficiency relies heavily on active layer material properties.
• Chlorophyll derivatives offer abundant, eco-friendly organic molecular materials for OSCs.

Purpose of the Study:

• To evaluate bacteriochlorin and its derivatives as potential donor materials in OSCs.
• To investigate the impact of non-fullerene acceptor (NFA) structure on photovoltaic performance.
• To computationally design efficient bulk heterojunctions (BHJs) for improved OSCs.

Main Methods:

• Density Functional Theory (DFT) for ground state structure optimization.
• Time-Dependent Density Functional Theory (TD-DFT) for calculating absorption spectra and excited state properties.
• Comparative analysis of donor and acceptor properties, and simulation of six BHJs.

Main Results:

• Bacteriochlorin demonstrated superior donor properties over D18, with better structural characteristics, smaller energy gap, lower hole reorganization energy, redshifted absorption, and higher hole mobility.
• o-AT-2Cl exhibited superior acceptor properties compared to m-AT-2Cl, highlighting the influence of substitution positions on NFA physicochemical properties.
• Bacteriochlorin-based BHJs showed promising performance, with BChl3/o-AT-2Cl and BChl4/o-AT-2Cl achieving the highest interfacial charge separation rates.

Conclusions:

• Bacteriochlorin and specific NFAs, particularly o-AT-2Cl, are suitable for high-performance OSCs.
• BHJs incorporating bacteriochlorin and NFAs offer a viable strategy for enhancing OSC photovoltaic performance.
• Computational modeling provides a pathway for designing efficient organic solar cell materials.