Extraction Current Transients for Selective Charge-Carrier Mobility Determination in Non-Fullerene and Ternary Bulk Heterojunction Organic Solar Cells

The field of organic solar cells has recently gained broad research interest due to the introduction of non-fullerene small-molecule acceptors. The rapid improvement in solar cell efficiency put increased demand on moving toward scalable device architectures. An essential step toward this is enabling thicker active layers for which the hole and electron mobilities and their ratio become increasingly important. In this work, we demonstrate selective charge-carrier mobility determination using the charge extraction by a linearly increasing voltage (CELIV) method. By tuning the contact properties of the solar cell diodes, the hole and electron mobilities are determined separately using the recently developed metal-intrinsic semiconductor-metal-CELIV (MIM-CELIV) technique. Balanced mobility is measured both in non-fullerene and in ternary blends with the recently published PBBF11 polymer. The mobility results are confirmed using the well-established metal-insulator-semiconductor (MIS) and photo-CELIV techniques.