Nonfullerene Ternary Organic Photovoltaics with Long-Wavelength Light-Absorption Guest Donor Materials to Improve Photovoltaic Performance

Abstract

In order to achieve efficient organic photovoltaics (OPVs), a ternary strategy was adopted with the efficient long-wavelength light-absorption donor material of PSBTBT as the third component material (guest donor) and the D18-Cl:BTP-eC9 binary film as the host photoactive layer, which facilitates the acquisition of absorption spectra complementary to those of D18-Cl and BTP-eC9. The PL spectrum of D18-Cl was covered by the absorption spectrum of PSBTBT, which further supports the energy transfer from D18-Cl to PSBTBT. In addition, the addition of a small amount of PSBTBT to the D18-Cl:BTP-eC9 binary film slightly changed the bulk and surface morphology of the photoactive layer, while appropriate phase separation size and a smooth surface could be achieved for both the D18-Cl:BTP-eC9 binary film and the optimized ternary film. Thus, with 10% PSBTBT as the third component material (D18-Cl/PSBTBT/BTP-eC9 ratio of 0.9:0.1:1.2), the ternary OPV shows a higher power conversion efficiency (PCE) of 17.35%. The improvement of photovoltaic performance is due to the short-circuit current density (J SC ) enhancement from 24.65 to 26.23 mA cm −2 , even though the open-circuit voltage (V OC ) weakly decreased from 0.905 to 0.900 V. This work provides an effective method to find a guest polymer that matches the host binary photoactive layer, broadens the absorption spectrum, and provides efficient energy transfer within both donor materials.

Conjugated polymers with near-infrared (NIR) optical absorption: structural design considerations and applications in organic electronics

“…P83–P86 all possess the CDT donor and various functionalized BT acceptor units with λ max /E g ranging from 702–920 nm/1.20–1.54 eV. 280–288…”

“…More recently, P90 (PSBTBT) was incorporated into ternary solar cells with the donor polymer D18-Cl and small-molecule acceptor BTP-eC9. 288 In this setting, P90 (PSBTBT) provided complementary energy levels to the other components enabling efficient charge transfer and more complimentary spectral coverage across the visible wavelength range and into the NIR. Thus, an excellent PCE of 17.35% was obtained.…”

Complementary Absorption Pseudo‐Ternary Blend Containing a Y‐Series Block Copolymer Acceptor for Indoor and Outdoor All‐Polymer Photovoltaics

“…Many studies have introduced ternary blend active layers with complementarily absorbing third components to enhance light absorption efficiency and device performance. [29][30][31][32] In addition to broadening the absorption range of the active layer, the introduction of a third component into a binary donor-acceptor blend can also enhance the film morphology, create an energy-level cascade, and improve charge/energy transfer. [33,34] Besides the PCE, the additional components can also improve the stretchability as well as mechanical and thermal stability of the device.…”