Highly Efficient Organic Photovoltaics Enhanced Using Organic Passivation Layer Vacuum Deposition

Abstract

Despite the tremendous development of various high-performing photoactive layers in organic photovoltaic (OPVs) cells, improving their performance remains the most important challenge in the field. Here, an effective and compatible strategy (i.e., the concept of vacuum deposition of an organic passivation layer (OPL) on the photoactive layer) is presented to enhance the efficiency of the state-of-the-art photoactive systems, where easy-deposition processable T2-ORH and T2-CNORH OPLs are used. After the deposition process, T2-ORH forms 2D-like edge-on crystalline structure, and the 3D-like face-on crystalline growth is induced in T2-CNORH. Resulting from its relatively higher crystalline features and increased wettability with the cathode interfacial material, the performance of T2-CNORH-deposited OPVs with both small and the scaled-up areas surpass devices without OPL and with T2-ORH. Experimental studies are conducted linking conductivity, electroluminescence quantum efficiency, carrier transport, and recombination dynamics to find the reasons for the performance difference. Furthermore, by applying the T2-CNORH to other photoactive platforms, the efficiencies are enhanced by 4.4-9.0% relative to those of the corresponding control devices; an optimal 16.4% efficiency is achieved, which validates its great applicability for photoactive layers that will be developed in the near future.