Organic photovoltaic devices with the bilayer cathode interfacial structure of pyromellitic dianhydride and lithium fluoride

In this study, we fabricated and characterized an organic photovoltaic (OPV) device with a pyromellitic dianhydride (PMDA)/lithium fluoride (LiF) cathode interfacial layer between poly(3-hexylthiophene2,5-diyl)(P3HT)+[6,6]- phenyl C ₆₁butyric acid methyl ester (PCBM) and Al. Compared to the OPV device with a LiF-only cathode interfacial layer having a power conversion efficiency (PCE) of 2.7%, the OPV device with the bilayer cathode interfacial structure [PMDA (0.3nm)/LiF (0.7nm)] exhibited a reduced resistance and a PCE value enhanced to 3.9% under an illumination condition of 100 mW cm ²(AM1.5). The observed improvement of the OPV characteristics was attributed to the reduced leakage current of the device by the bilayer cathode interfacial layer.