Structure-Property Correlation: A Comparison of Charge Carrier Kinetics and Recombination Dynamics in All-Polymer Solar Cells

Abstract

We report a comparison of charge carrier kinetics and recombination dynamics correlated with the device performances of PBDTTT-C and PBDTTT-CT in nonfullerene P(NDI2OD-T2) solar cells. The nanoscale morphological characteristics are found to be remarkably different for these two polymers in all-polymer bulk heterojunction (BHJ) blends. Important insights into the carrier dynamics and crystalline packing features of these different donor materials are provided in detail. The higher device performance of the PBDTTT-CT:P(NDI2OD-T2) device [2.78% compared to 1.56% for the PBDTTT-C:P(NDI2OD-T2) cell] is shown to result from efficient charge generation and faster carrier separation, reducing nongeminate recombination during charge collection, which is attributed to the perfect intermixing between the donor and acceptor polymer networks.