Rational Anode Engineering Enables Progresses for Different Types of Organic Solar Cells

Anode modification is vital for improving device performance of organic solar cells (OSCs). PEDOT:PSS is the most widely applied hole transport layer (HTL) in OSCs. In this work, three kinds of modified HTLs, namely PEDOT:PSS-PA, PEDOT:PSS-TA, and PEDOT:PSS-DA are readily prepared via simple doping of phenylethylamine derivatives into commercially available Al 4083, by modulating the number of hydroxyl groups on the adulterant molecules. All of them exhibit enhanced work functions (WFs) and conductivities. Matching with PM6:Y6 composed active layers, PEDOT:PSS-TA based devices achieves the highest performance with a power conversion efficiency (PCE) of 17.10%, while the PM6:ITC-2Cl system demonstrates a highest PCE of 14.17% in devices with PEDOT:PSS-DA, and the optimal PCE of PM6:PIDTC-T based OSCs is equal to 9.55% while the HTL is PEDOT:PSS-PA. Further investigations reveal that the different adulterants formed various amount of hydrogen bonds in HTLs, inducing dissimilar interfacial morphology and mobility, and thus unidentical degrees of change in recombination. Afterwards, the doping strategy is extended to a newly proposed high-performance system PM6:PY-IT, and successfully drags its efficiency from 14.78% to 15.62%, another world-class breakthrough for all-polymer solar cells. In summary, this study not only achieves a series of OSCs with improved PCEs, but also delivers a deep understanding of PEDOT:PSS improvement.