1 research outputs found
Thermal Annealing Effect on Ultrafast Charge Transfer in All-Polymer Solar Cells with a Non-Fullerene Acceptor N2200
Ultrafast transient absorption (TA)
spectroscopy was employed to
investigate the thermal annealing effect on the charge transfer (CT)
in bulk heterojunction (BHJ) all-polymer solar cells (all-PSCs) utilizing
an n-type polymer PÂ(NDI2OD-T2) (Polyera, N2200) as acceptor and a
low bandgap polymer PBPT as donor. The CT generates hole polarons
residing in the PBPT and electron polarons belonging to N2200, manifested
in the TA spectra of the BHJ films as the long-lived absorption peak
centered at ∼850 nm. The CT is most efficient in the film annealed
at 160 °C and its efficiency declines monotonically when enhancing
or reducing the annealing temperature, displaying a positive correlation
with the power conversion efficiency (PCE) of the corresponding solar
cell devices. This correlation is analyzed in terms of the crystallinity
and phase separation, which are the key factors determining the performance
of all-PSCs. Our results can provide valuable guidance for the fabrication
of BHJ all-PSCs to improve their PCE