Spontaneous emission

Electrical engineering

Physics

Energy conversion efficiency

Laser

Organic solar cell

Optics

Semiconductor

Non-radiative recombination

Engineering

Composite material

Renewable energy

Solar cell efficiency

Materials science

Semiconductor materials

Solar cell

Optoelectronics

Polymer

Radiative transfer

Nature Photonics

Energy loss within organic solar cells (OSCs) is undesirable as it reduces cell efficiency1–4. In particular, non-radiative recombination loss3 and energetic disorder5, which are closely related to the tail states below the band edge and the overall photon energy loss, need to be minimized to improve cell performance. Here, we report how the use of a small-molecule acceptor with torsion-free molecular conformation can achieve a very low degree of energetic disorder and mitigate energy loss in OSCs. The resulting single-junction OSC has an energy loss due to non-radiative recombination of just 0.17 eV and a high power conversion efficiency of up to 16.54% (certified as 15.89% by the National Renewable Energy Laboratory). The findings take studies of organic photovoltaics deeper into a new regime, beyond the limits of energetic disorder and large energy offset for charge generation. An organic solar cell designed with minimal energetic disorder exhibits very low energy loss due to non-radiative recombination and highly efficient operation.

High-efficiency organic solar cells with low non-radiative recombination loss and low energetic disorder