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Theoretical design of non-fullerene small molecule acceptors for organic solar cells with improved efficiency.

Theoretical design of non-fullerene small molecule acceptors for organic solar cells with improved efficiency.

Objective

Organic solar cells are lightweight, mechanically flexible and potentially printable devices. To split an exciton, these cells use a mixture of electron donor and acceptor materials. At present, most of the electron acceptors are made up of fullerenes or their derivatives. However, fullerenes exhibit only weak light absorption in the visible spectrum. Hence, practically half of the active material in the solar cell does not collect light and thus does not contribute to exciton and charge generation, thereby limiting the maximum efficiency of organic solar cells to 12%.
Recent experimental and theoretical works show that it is possible to improve this low efficiency by replacing fullerene acceptors with small molecules (strong dyes). These strong dyes can change the energy profile of the donor-acceptor interface in a way that improves the solar cell behavior by causing it to favor more efficient charge-transferred state splitting. The mechanism by which the efficiency is improved is complex and not well-understood and is mediated by the strong dye’s ability to alter the electrostatic forces felt by generated excitons. However, a rational approach to design such non-fullerene acceptors on a molecular level, accounting for the complex electrostatic interactions, has not been developed.
In-depth molecular level understanding of donor-(non-fullerene) acceptor interfaces, including long-range electrostatic effects, is the first goal of this proposal. It will include simulations of morphologies and evaluation of electrostatic forces at donor-non-fullerene acceptor interfaces for several experimentally well-characterized systems. The second step will include the design of a pre-screening workflow for new acceptors, focusing on the optimization of the efficiency of the charge-transferred state splitting and minimization of the open circuit voltage losses.
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Coordinator

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV

Address

Hofgartenstrasse 8
80539 Muenchen

Germany

Activity type

Higher or Secondary Education Establishments

EU Contribution

€ 174 806,40

Project information

Grant agreement ID: 844655

Status

Grant agreement signed

  • Start date

    1 December 2019

  • End date

    30 November 2021

Funded under:

H2020-EU.1.3.2.

  • Overall budget:

    € 174 806,40

  • EU contribution

    € 174 806,40

Coordinated by:

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV

Germany