Voltage

Acceptor

Engineering

Chemical physics

Short circuit

Materials science

Physics

Nanotechnology

Charge carrier

Condensed matter physics

Heterojunction

Chemistry

Energy conversion efficiency

Organic solar cell

Photovoltaics

Optoelectronics

Photovoltaic system

Electrical engineering

Nature Communications

The chemical structure of donors and acceptors limit the power conversion efficiencies achievable with active layers of binary donor-acceptor mixtures. Here, using quaternary blends, double cascading energy level alignment in bulk heterojunction organic photovoltaic active layers are realized, enabling efficient carrier splitting and transport. Numerous avenues to optimize light absorption, carrier transport, and charge-transfer state energy levels are opened by the chemical constitution of the components. Record-breaking PCEs of 18.07% are achieved where, by electronic structure and morphology optimization, simultaneous improvements of the open-circuit voltage, short-circuit current and fill factor occur. The donor and acceptor chemical structures afford control over electronic structure and charge-transfer state energy levels, enabling manipulation of hole-transfer rates, carrier transport, and non-radiative recombination losses.

Single-layered organic photovoltaics with double cascading charge transport pathways: 18% efficiencies