Sulfonate-Conjugated Polyelectrolytes as Anode Interfacial Layers in Inverted Organic Solar Cells

Abstract

Conjugated polymers with ionic pendant groups (CPEs) are receiving increasing attention as solution-processed interfacial materials for organic solar cells (OSCs). Various anionic CPEs have been successfully used, on top of ITO (Indium Tin Oxide) electrodes, as solution-processed anode interlayers (AILs) for conventional devices with direct geometry. However, the development of CPE AILs for OSC devices with inverted geometry is an important topic that still needs to be addressed. Here, we have designed three anionic CPEs bearing alkyl-potassium-sulfonate side chains. Their functional behavior as anode interlayers has been investigated in P3HT:PC61BM (poly(3-hexylthiophene): [6,6]-phenyl C61 butyric acid methyl ester) devices with an inverted geometry, using a hole collecting silver electrode evaporated on top. Our results reveal that to obtain effective anode modification, the CPEs’ conjugated backbone has to be tailored to grant self-doping and to have a good energy-level match with the photoactive layer. Furthermore, the sulfonate moieties not only ensure the solubility in polar orthogonal solvents, induce self-doping via a right choice of the conjugated backbone, but also play a role in the gaining of hole selectivity of the top silver electrode.

Water‐Soluble Organic Dyes as Efficient Anode Interlayer Materials for PEDOT:PSS‐Free Inverted Bulk Heterojunction Solar Cells

“…It is worth noting that the use of EtOH or water/EtOH is quite limited also in the field of polymeric AILs, which are more often deposited from the more toxic MeOH, [ 36 ] MeOH/acetic acid, [ 37 ] or MeOH/water solutions. [ 38 ]…”

“…It is worth noting that the use of EtOH or water/EtOH is quite limited also in the field of polymeric AILs, which are more often deposited from the more toxic MeOH, [36] MeOH/acetic acid, [37] or MeOH/water solutions. [38] To verify which polar solvent or solvent mixture can be employed to process SBF derivative top hole transport layers for inverted OSC architectures, we first measured the contact angles (CAs) of various AIL solutions and PEDOT:PSS suspensions deposited on the surface of PTB7-Th:ITIC active layers (Figure 4). Note that similar results were obtained for both SBF derivatives, but the images in Figure 4 correspond to compound 1.…”

Organic Functionalized Carbon Nanostructures for Solar Energy Conversion

“…Considerable progress has been achieved by both developing new materials for the active layers; for example, non-fullerenic acceptor systems [ 84 ] in organic photovoltaics (OPV) or the use of perovskites in hybrid cells (PSC) [ 85 ], and also by engineering the interfaces with the electrodes using layers that can act as HTMs (hole-transporting materials) or ETMs (electron-transporting materials) [ 86 , 87 , 88 ].…”

Organic Functionalized Carbon Nanostructures for Solar Energy Conversion

“…Considerable progress has been achieved both by developing new materials for the active layers, see for example non-fullerenic acceptor systems [69] in organic photovoltaics (OPV) or the use of perovskites in hybrid cells (PSC) [70], but also by engineering the interfaces with the electrodes using layers that can act as HTM (hole transporting materials) or ETM (electron transporting materials) [71][72][73].…”