Figure 1: Characterization of three DT-BT-based polymers.
From: A polymer tandem solar cell with 10.6% power conversion efficiency
(a) Chemical structures of three different polymers (PCPDT-BT, PCPDT-DFBT and PDTP-DFBT) based on DT-BT backbone. (b) Normalized absorption spectra of the three polymers PCPDT-BT (black line), PCPDT-DFBT (red line) and PDTP-DFBT (blue line) spin-coated on glass substrate. (c) Electrochemical cyclic voltammogram of PCPDT-BT (black line) PCPDT-DFBT (red line) and PDTP-DFBT (blue line). The red arrows indicate the potential onset of the oxidation or reduction reactions in the electrochemical measurements. On the basis of equation (see Methods) it can be calculated the HOMO and the LUMO for PCPDT-BT are −5.18 and −3.56 eV, respectively; for PCPDT-DFBT, the HOMO and LUMO are −5.34 and −3.52 eV, respectively; for PDTP-DFBT, the HOMO and LUMO are −5.26 and −3.61 eV, respectively. a.u., arbitrary unit.
