Chemistry

Ecology

Materials science

Optoelectronics

Engineering

Composite material

Physics

Nanotechnology

Organic chemistry

Energy conversion efficiency

Biology

Solubility

Acceptor

Photovoltaic system

Polymer solar cell

Hildebrand solubility parameter

Active layer

Annealing (glass)

Condensed matter physics

Chemical engineering

Layer (electronics)

Polymer

Thin-film transistor

ACS Energy Letters

The performance of polymer solar cells (PSCs) is commonly improved using additives or annealing treatment. However, these processes are accompanied by disadvantages, including poor reproducibility and stability. Herein, a molecular design strategy is proposed to obtain additive- and annealing-free PSCs. IDTOT2F containing two alkoxyl side chains at the central unit of the nonfullerene acceptor IDTT2F was developed. This molecular design results in excellent solubility in solutions, ordered molecular packing in films, slightly elevated energy levels, and a higher film absorption coefficient. Compared with its counterpart IDTT2F, its improved solubility provides an active layer with better morphology, its ordered molecular packing enhances the charge mobility in blend films, and its slightly elevated energy level furnishes a higher open-circuit voltage of devices. As a result, IDTOT2F-based devices display a maximum power conversion efficiency of 12.79%, which is one of the highest values reported for a PSC fabricated without any extra treatment.

Nonfullerene Acceptors with Enhanced Solubility and Ordered Packing for High-Efficiency Polymer Solar Cells