Most of the recent organic solar cells (OSCs) with top‐of‐the‐line efficiencies are processed from organic solvents with a high vapor pressure such as CF in nitrogen‐filled glovebox, which is not feasible for large‐area manufacturing. Herein, we cast active layers with both aromatic hydrocarbon solvents and halogenated solvents without any solvent additive or post‐treatment, as well as interlayers with water and methanol in air (35% relative humidity) for efficient OSCs, except cathode electrode's evaporation is in vacuum. Compared to the PM6:Y6 system that is processed from CF, the PM6:BTP‐ClBr2 system demonstrates good efficiency of 16.28% processed from CB and the device based on PM6:BTP‐4Cl achieves 16.33% using TMB as its solvent for the active layer. These are among the highest efficiencies for CB‐ and TMB‐processed binary OSCs to date. The molecular packing and phase separation length scales of each combination depend strongly on the solvent, and the overall morphology is the result of the interplay between solvent evaporation (kinetics) and materials miscibility (thermodynamics). Different solvents are required to realize the optimal morphology due to the different miscibility between the donor and acceptor. Finally, 17.36% efficiency was achieved by incorporating PC71BM for TMB‐processed devices. Our result provides insights into the effect of processing solvent and shows the potential of realizing high‐performance OSCs in conditions relevant for industrial fabrication.
PEDOT:PSS is the most popular hole-transporting material (HTM) for conventional structural organic solar cell (OSC) devices, whose performance is of great importance for realizing high power conversion efficiency (PCE). However, its performance in OSC devices has been continuously challenged by various replacing materials and different doping strategies, for better conductivity, work function, and surface property. Here, we report a simple dopant-free method to tune the phase separation of the PEDOT:PSS layer, which results in better charge transport and extraction in devices. Specifically, high PCEs for binary polymersmall-molecule (>18%) and polymer−polymer (>17%) systems are simultaneously achieved. This work engineeringly provides encouraging improvement for OSC device performance with easy modification and scientifically offers insights into tuning the property of the PEDOT:PSS layer.
The effects of oxidant(ammonia persulfate)/aniline ratio and reaction temperature on the yield, oxidation state, solubility in NMP and the properties of the films made from NMP solution were studied. The yields of polyaniline reach a maximum when oxidant/aniline ratio equals to 1.25 and reaction temperature is -5 C. The solubilities of polyaniline base form also reach a maximum at oxidant/aniline ratio of 1.25 and reaction temperatures of -5 C and 0 C. The ratios of benzene ring and quinoid ring are the same for polyaniline synthesized with oxidant/aniline ratio lower than 1.25. When the ratio of oxidant/aniline is higher than 1.75, the film can hardly be formed from NMP solution. Polyaniline films can be stretched to higher ratio when oxidant/aniline ratios are lower and reaction temperatures are -5 C and 0 C. Thermal stability and mechanical strength of polyaniline increase in the presence of a small amount of NMP.Poly(p-phenylene) (PPP) films were obtained by the electrochemical polymeiization of benzene in nitromethane. The as-grown films were p-type. Structures and properties of the films were found to depend significantly on the polymerization potentia1 and the supporting electrolyte. Electrical conductivities of the films were measured in both plane and vertical directions. With a n increase in the polymerization potential, the DC conductivities in a plane direction increased, whereas those in a vertical direction decreased. The AC conductivities were also measured in the range from 0.1 to 1 OOCl KHz. The AC conductivities showed the anisotropy as well as the DC conductivities. It was possible to obtain n-type films by cation-doping. The band structures of the PPP films were calculated from the optical properties and the cyclic voltammograms.
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