Electrical engineering

Physics

Organic chemistry

Polymer chemistry

Energy conversion efficiency

Absorption (acoustics)

Engineering

Voltage

Band gap

Composite material

Chemistry

Materials science

Condensed matter physics

Benzotriazole

Acceptor

Electron acceptor

Polymerization

Polymer solar cell

Chemical engineering

Optoelectronics

Polymer

Short circuit

Photochemistry

Journal of the American Chemical Society

Despite the significant progresses made in all-polymer solar cells (all-PSCs) recently, the relatively low short-circuit current density (Jsc) and large energy loss are still quite difficult to overcome for further development. To address these challenges, we developed a new class of narrow-bandgap polymer acceptors incorporating a benzotriazole (BTz)-core fused-ring segment, named the PZT series. Compared to the commonly used benzothiadiazole (BT)-containing polymer PYT, the less electron-deficient BTz renders PZT derivatives with significantly red-shifted optical absorption and up-shifted energy levels, leading to simultaneously improved Jsc and open-circuit voltage in the resultant all-PSCs. More importantly, a regioregular PZT (PZT-γ) has been developed to achieve higher regiospecificity for avoiding the formation of isomers during polymerization. Benefiting from the more extended absorption, better backbone ordering, and more optimal blend morphology with donor component, PZT-γ-based all-PSCs exhibit a record-high power conversion efficiency of 15.8% with a greatly enhanced Jsc of 24.7 mA/cm2 and a low energy loss of 0.51 eV.

High Efficiency (15.8%) All-Polymer Solar Cells Enabled by a Regioregular Narrow Bandgap Polymer Acceptor