Energetic Disorder and Activation Energy in Efficient Ternary Organic Solar Cells with Nonfullerene Acceptor Eh-IDTBR as the Third Component

摘要

Solution-processed ternary organic solar cells (OSCs) contain a third component inthe active layer in addition to the donor/acceptor materials. Two main avenues areconsidered to fabricate ternary OSCs: 1) to improve the short-circuit current densityby the selected third component that broadens and/or enhances the absorption ofthe host films and 2) to increase the fill factor by adding materials with diversecrystallinity to tune the film morphology. However, little work is reported for theimprovement of open-circuit voltage (V_∝), energetic disorder, charge transfer stateenergy (E_(CT)), and activation energy in ternary OSCs. Herein, ternary OSCs withactive layer composed of PCE10:F8IC:Eh-IDTBR as the model to examine theseparameters in addition to the morphology are used. In the ternary device, theadditional Eh-IDTBR improves the crystallinity of the acceptor phase in the ternarymixture; the V_∝ is 58 mV higher than that of the reference caused by the reducedenergetic disorder; due to the good miscibility of Eh-IDTBR with both PCE10 andF8IC, only 50 meV in ECT is observed; and the zero-field activation energy is lowerthan that for the reference. The findings provide an alternative way to understandthe complex ternary OSC structural–electrical properties’ correlations.