Spontaneous carrier generation and low recombination in high-efficiency non-fullerene solar cells

Abstract

The current research reveals the unique photo physical properties and carrier generation mechanisms of high efficiency non-fullerene acceptor based organic photovoltaic blends. The analysis of device performance, morphology, and photo...

Picosecond Charge-Transfer-State Dynamics in Wide Band Gap Polymer–Non-Fullerene Small-Molecule Blend Films Investigated via Transient Infrared Spectroscopy

“…Although in the literature a considerable non-geminate recombination has been observed for BTP-4F, it highly depends on the thin film morphology. 35 Therefore, our findings point toward a morphologydependent difference of the charge mobilities in PTQ-2F and BTP-4F, suppressing the non-geminate recombination in BTP-4F in our experiments.…”

“…A comparison with the neat PTQ-2F and BTP-4F films (see Supporting Figures S5 and S6) reveals that the higher order effects appear to originate in the donor polymer PTQ-2F, as the neat small-molecule acceptor BTP-4F shows no changes in its tens of picoseconds dynamics with increasing excitation density. Although in the literature a considerable non-geminate recombination has been observed for BTP-4F, it highly depends on the thin film morphology …”

“…We find that the Fano resonance signal exhibits an additional dynamic on the order of a few to a few tens of picoseconds. This additional process can only be found in an active layer BHJ composition but not for the neat materials that also exhibit polaron formation , (see Supporting Figure S8). Therefore, we conclude that its physical origin lies within the charge-transfer process between the electron donor PTQ-2F and the electron acceptor molecule BTP-4F, which is only present in the BHJ geometry.…”

N-dopants optimize the utilization of spontaneously formed photocharges in organic solar cells

“…According to recent progress from Hodgkiss and Liu et al, severe bimolecular recombination dominates the performance loss in neat Y6 and ultralow donor-content dilute PM6/Y6 films. 15,43 We next looked into the role of n-dopant on spontaneous photocharge bimolecular recombination in the framework of 1% PM6-content dilute BHJ devices. We assumed that the asymmetric composition of the dilute BHJ film leads to unbalanced carrier extraction ability, and severe bimolecular Energy & Environmental Science Paper recombination occurs due to the formation of the space-charge region.…”

Surface Charge and Nanoparticle Chromophore Coupling to Achieve Fast Exciton Quenching and Efficient Charge Separation in Photoacoustic Imaging (PAI) and Photothermal therapy (PTT)

“…[38][39][40][41] When rapped in a surfactant shell, stronger pipi stacking is observed, which splits into multiple modes, and results in improved excitons and carrier diffusion. The strong intermolecular interaction leads to new lower energetic states, [42][43][44] and the photon emission gets extended over than 130 nm comparing to thin film solids. The sub-bandgap states (emission over 1100 nm) afford new possibilities in photon acoustic imaging, since deeper tissue penetration can be achieved.…”