Charge transfer in organic molecules for solar cells: theoretical perspective

Area of Science:

• Physical Chemistry
• Materials Science
• Organic Electronics

Background:

• Efficient charge transfer and separation in organic molecules are crucial for developing advanced solar cells.
• Understanding the fundamental principles governing these processes is essential for optimizing device performance.

Purpose of the Study:

• To provide a tutorial review of rate theories for charge transfer and separation in organic molecules.
• To elucidate the relationship between electronic coupling, reorganization energy, and charge transfer rates.
• To discuss computational methods for calculating key parameters in charge transfer processes.

Main Methods:

• Application of Fermi's golden rule for weak electronic coupling.
• Analysis of microcanonical and canonical rates, including the Marcus formula.
• Exploration of rate approaches beyond the perturbation limit.
• Utilizing electronic structure theory for calculating electronic coupling and reorganization energy.

Main Results:

• Demonstration of how electronic coupling and reorganization energy influence charge transfer rates.
• Illustration of the impact of molecular bridges on charge transfer dynamics.
• Presentation of various theoretical frameworks for predicting charge transfer rates.

Conclusions:

• Rate theories provide a robust framework for understanding and predicting charge transfer in organic solar cells.
• Electronic structure calculations are vital for accurate determination of parameters governing charge transfer.
• This review serves as a guide for researchers in the field of organic electronics and photovoltaics.