A Platinum (II) Polyyne Oligomers Donor for Efficient Ternary Organic Solar Cells

A ternary organic solar cell (TOSC) P5 :PC ₇₁ BM:Y6 (1:0.2:1) composed of an electron donor 3,4‐ethylenedioxythiophene (EDOT)/diketopyrrolopyrrole (DPP)‐containing [Pt] (II) polyyne oligomer P5 with the acceptors PC ₇₁ BM and Y6 shows a significant enhancement of the average power conversion efficiency (PCE) to 16.0% in comparison to the reported binary organic solar cells (OSCs) ( P5 :PC ₇₁ BM (1:1.4), PCE = 9.4%; P5 :Y6 (1:1.2), PCE = 14.8%). Photophysical investigations carried out on the two binaries and on the ternary highlight the role of PC ₇₁ BM to increase the rise time of electron transfer and to decrease recombination processes. Investigations of Y6‐containing active layers by atomic force microscopy (AFM) and high‐resolution transmission electron microscopy (HR‐TEM) show the presence of fibers, which highlights the assistance of Y6 in the nanostructuration of the blends. The higher PCE of the TOSC is explained with larger values of short‐circuit current density ( J _SC ) from a broader absorption range and a superior value of fill factor (FF) supported by the faster mobilities and more balanced µ _e / µ _h . This work spotlights the beneficial role of the two acceptors in the TOSC. It explains the achievement of the highest average PCE of 16.0% for [Pt] polyyne oligomers to this date.