Recent Developments of Polymer Solar Cells with Photovoltaic Performance over 17%

Abstract

With the emergence of ADA'DA-type (Y-series) non-fullerene acceptors (NFAs), the power conversion efficiencies (PCEs) of organic photovoltaic devices have been constantly refreshed and gradually reached 20% in recent years (19% for single junction and 20% for tandem device). The acceptors possess specific design concept, which greatly enrich the NFA types and have excellent compatibility with many donor materials. It is gratifying to note that the previously underperforming donor materials combine with these regulated acceptors to shine again. Nowadays, the concept of modular design is widely used in the research of acceptors and donors, injecting new vitality into the field of organic photovoltaics. Furthermore, these acceptors also promote the research of multicomponent devices, tandem devices, bilayer devices, processing solvent engineering, and additive engineering. Herein, the latest progresses of polymer solar cells with efficiency over 17% are briefly reviewed from the aspects of active material design, interface material development, and device technology. At last, the opportunities and challenges of organic photovoltaic commercialization in the future are discussed.

Regioregular polymerized small-molecule acceptors for high-performance all-polymer solar cells

“…47,48 Halogenation of terminal groups with different numbers of halogen atoms or in different attached positions is commonly used to regulate the electron push-pull capacity, modulate the molecular energy level and blend morphology, which has obvious advantages in improving device performance. 49 Yan and co-workers designed and synthesized two regioregular PSMAs named PYF-T-o and PYF-T-m (Fig. 3) with fluoro-and bromosubstituted 1,1-dicyanomethylene-3-indanone (IC-FBr-o or IC-FBr-m) as the terminal groups.…”

“…47,48 Halogenation of terminal groups with different numbers of halogen atoms or in different attached positions is commonly used to regulate the electron push–pull capacity, modulate the molecular energy level and blend morphology, which has obvious advantages in improving device performance. 49…”

Understanding and Suppressing Non‐Radiative Recombination Losses in Non‐Fullerene Organic Solar Cells

“…The currently highest efficiency, Y-series of non-fullerene acceptors (NFA), however, enables OSCs with high external quantum efficiencies (EQE PV ) and fill factors (FF) at a marginal ΔE S1,CT . [8][9][10][11] NFAs benefit from a combination of good charge transport properties, optimized film morphologies, as well as high absorption coefficients, up to 1.5 × 10 5 cm −1 (compared to 1.0-5.0 × 10 4 cm −1 for fullerenes) in the visible and near-infrared. [8,[12][13][14] An additional and significant advantage in the optimization of the photovoltaic properties of donor: NFA blends are their relatively straightforward adjustment of the frontier energy levels and optical gaps over a wide energy range, by engineering acceptor-donor-acceptor (A-D-A) or A-DA'D-A-type (such as Y6) fused groups in their molecular backbones.…”

“Twisted” small molecule donors with enhanced intermolecular interactions in the condensed phase towards efficient and thick-film all-small-molecule organic solar cells

“…However, most ASM-OSCs show power conversion efficiencies (PCEs) below 15%, which signicantly lag behind those of OSCs based on polymer donors. [8][9][10][11][12][13][14][15] In addition, the device efficiency of ASM-OSCs is oen more sensitive to the thickness of the active layers than that of OSCs containing polymer components. The inferior PCE and the high sensitivity of the device performance to lm thickness for ASM-OSCs are mainly derived from the unideal lm morphology.…”