Highly Crystalline Near-Infrared Acceptor Enabling Simultaneous Efficiency and Photostability Boosting in High-Performance Ternary Organic Solar Cells

Abstract

The near-infrared (NIR) absorbing fused-ring electron acceptor, COi8DFIC, has demonstrated very good photovoltaic performance when combined with PTB7-Th as a donor in binary organic solar cells (OSCs). In this work, the NIR acceptor was added to state-of-the-art PBDBT-2F:IT4F-based solar cells as a third component, leading to (i) an efficiency increase of the ternary devices compared to the binary solar cells in the presence of the highly crystalline COi8DFIC acceptor and (ii) much-improved photostability under 1-sun illumination. The electron transport properties were investigated and revealed the origin of the enhanced device performance. Compared to the binary cells, the optimized ternary PBDBT-2F:COi8DFIC:IT4F blends exhibit improved electron transport properties in the presence of 10% COi8DFIC, which is attributed to improved COi8DFIC molecular packing. Furthermore, transient absorption spectroscopy revealed a slow recombination of charge carriers in the ternary blend. The improved electron transport properties were preserved in the ternary OSC upon aging, while in the binary devices they seriously deteriorated after simulated 1-sun illumination of 240 h. Our work demonstrates a simple approach to enhance both OSC efficiency and photostability.

Reproducibility in Time and Space—The Molecular Weight Effects of Polymeric Materials in Organic Photovoltaic Devices

“…GDM was employed to extract the energetic disorder σ h , which is expressed as where μ 0 is zero‐field mobility, μ ∞ is high‐temperature limit mobility, k B is the Boltzmann constant, and T is the temperature. [ 40,41 ] We performed the hole‐only device with four individual active areas, and the device structure is shown in Figure S1 in the Supporting Information. As shown in Figure , σ h values increase with polymeric molecular weight decreasing.…”

Benzodithiophene-Based Small-Molecule Donors for Next-Generation All-Small-Molecule Organic Photovoltaics

“…This strategy, which introduces a third component into the donor/acceptor binary materials, can broaden absorption, improve exciton dissociation, facilitate charge transport, and fine-tune the BHJ active-layer morphology toward enhanced photovoltaic performance. 3,92,[98][99][100][101][102][103][104][105][106] Generally, four models have been proposed on the role of the third component in the BHJ active layer of polymer OSCs: charge transfer, energy transfer, parallel linkage, and alloy models. 3,107 Also important is the molecular structural compatibility of the multiple components.…”

A facile and robust approach to prepare fluorinated polymer dielectrics for probing the intrinsic transport behavior of organic semiconductors

“…38 In this model, charges hop in an energetic manifold with a Gaussian density of states. The width of the manifold is s. Under such a condition, the charge carrier mobility is temperature (T) and electric field (F) dependent and the mobility can be expressed as: [38][39][40][41]…”