Fig. 4: Charge recombination and separation properties. | Nature Communications

Fig. 4: Charge recombination and separation properties.

From: Delocalization of exciton and electron wavefunction in non-fullerene acceptor molecules enables efficient organic solar cells

Fig. 4

a Photoluminescence spectra of the Y6, IT-4F, and ITIC films excited at 660 nm together with their quantum efficiencies. b Semi-logarithmic plots of EQE evaluated by FTPS (EQEFTPS) (black spheres) and normalized EL (dark yellow spheres) as a function of energy for devices based on PBDB-T-2F:Y6. The ratio of ϕEL/ϕbb was used to plot the EQE in the low energy regime (red line), where ϕEL and ϕbb represent the emitted photon flux and the room-temperature blackbody photon flux, respectively. The normalized PL spectra (orange lines) were measured based on the binary blend films. c Natural transition orbitals of the interfacial CT states by using the TD-ωB97XD/6-31G(d,p) method coupled with the PCM model for molecular clusters (left: one PBDB-T-2F donor fragment with one Y6 molecule; right: one PBDB-T-2F donor fragment with three Y6 molecules). Due to the delocalization of the electron wavefunction, the estimated distance (de–h) between the hole and electron at the donor/acceptor interface increases from 22 Å for one Y6 molecule to 51 Å for clusters of three Y6 molecules.

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