Structural Dynamics of Polymer:Non-Fullerene Organic Solar Cell Blends: A Neutron Spectroscopy Perspective

TL;DR

This study uses neutron spectroscopy to analyze the structural dynamics of non-fullerene acceptor-based organic solar cell blends, revealing similar dynamical responses among components, which correlates with improved device efficiency.

Contribution

It provides new insights into the structural dynamics of ADA-type NFA blends, highlighting their similar component behavior and contrasting with fullerene-based systems.

Findings

Similar dynamical response of blend components

Absence of vitrification in P3HT:NFAs blends

Correlation between dynamics and improved PCE

Abstract

Organic solar cells (OSCs) based on ADA-type (acceptor-donor-acceptor) non-fullerene acceptors (NFAs) exhibit improved power conversion efficiency (PCE) compared to the conventional fullerene-based analogues. The optoelectronic properties of OSC active layer blends are correlated to their underlying structural dynamics and therefore influence the device performance. Using synergistically different neutron spectroscopy techniques, we studied the dynamics of binary and ternary blends made of the NFAs O-IDTBR and O-IDFBR and the regioregular donor polymer P3HT. Deuteration was considered for a contrast variation purpose. In addition to shedding light on the miscibilty and alloying characters of the blends, a main outcome of this work is the evidenced similar dynamical response of the blend components. This finding is in contrast with our previous neutron spectroscopy and molecular dynamics studies of the fullerene-based blend P3HT:PCBM, where we highlighted distinct behaviors of P3HT and PCBM in terms of the vitrification/frustration of P3HT and the plasticization of PCBM by P3HT upon blending. Alike P3HT vitrification is not presently observed. The absence or the weak vitrification evidenced here is in line with recent reports and is likely related to the improved PCE exhibited by the ADA-type NFA-based OSCs.