ИСТИНА

Perovskite solar cells (PSCs) represent highly promising emerging photovoltaic technology. To achieve high power conversion efficiencies (PCE), new hole-transport layer (HTL) materials for PCSs have been actively designed and investigated. Along with spiro-OMeTAD, polytriarylamines (PTAAs) represent one of the most commonly used families of HTL materials. Unfortunately, both spiro-OMeTAD and PTAA are extremely expensive, with current prices of ~500-2000 $/g, due to multistep synthesis and the use of high cost catalysts and reagents. Methods typically utilized to synthesize PTAAs include the Pd-catalyzed Suzuki and Buchwald–Hartwig reactions, bis(cyclooctadiene)nickel-driven polymerization of brominated triarylamines, electrochemical polymerization, and the Ullman reaction. Compared to these methods, FeCl3-mediated oxidative polymerization of triarylamines is much more affordable. Although the oxidative polymerization of arylamines has been actively utilized for the synthesis of materials for electroluminescent devices, the application of this approach for the synthesis of HTL materials for perovskite solar cells remained unexplored. Here we present a series of polytriarylamines obtained by simple and cheap oxidative polymerization, that can be successfully utilized as hole transport materials for both p–i–n and n–i–p PSCs. The devices fabricated using the obtained polymers demonstrated high PCEs reaching 20%, which are comparable to or even higher than the efficiencies of the reference cells comprising high-cost commercial PTAAs synthesized using Suzuki polycondensation. The proposed approach allows to reduce the cost of polymeric hole transport materials to 50– 60 $/g or even below, thus bringing perovskite photovoltaics closer to commercialization.