Ternary All-Polymer Solar Cells with Two Synergetic Donors Enable Efficiency over 14.5%

Polymerized small-molecule acceptors (PSMAs) have recently drawn much attention and rapidly boost the power conversion efficiency (PCE) of all-polymer solar cells (all-PSCs). In this study, a low-cost polymer donor PTQ10 was employed as the third component (the second polymer donor) into the PBDB-T:PTPBT-ET 0.1 system (where PTPBT-ET 0.1 was a previously reported PSMA), and the ternary all-PSC achieved higher PCE of 14.56%. The component of PTQ10 not only leads to the extended absorption coverage but also shows excellent compatibility with PBDB-T. In addition, the highest occupied molecular orbital (HOMO) energy level of the PTQ10 donor is slightly lower than that of PBDB-T, leading to a higher open-circuit voltage. The performance of the ternary all-PSCs is primarily improved by the enhanced short-circuit current density ( J sc ) and open-circuit voltage ( V oc ), which can be attributed to the enhanced exciton dissociation and balanced charge transport in the presence of PTQ10. Therefore, the addition of a second wide bandgap polymer donor into a binary polymer donor/PSMA system could be an effective way to improve the photovoltaic performance of the all-PSCs.