Efficient ternary all small molecule organic photovoltaics with NC70BA as third component materials

Inverted small molecule organic photovoltaics (SMPVs) were fabricated with BTR as a donor, the narrow band gap material Y11 as an acceptor and NC(70)BA fullerene derivatives with a broad band gap as the third component materials. When 20 wt% Y11 was replaced by NC(70)BA, a higher PCE of 13.92% was achieved, which is attributed to simultaneous enhancement of the J(SC) of 22.16 mA cm(-2), the V-OC of 0.905 V and the FF of 69.4%. The hollow spherical structure of NC(70)BA may lead to the connection of Y11 and BTR molecules to form more continuous electron transport channels. Shallow lowest unoccupied molecular orbital (LUMO) energy levels form a cascade of LUMO energy levels among the used materials. In addition, the molecular arrangement and crystallinity in the photoactive layer can be markedly adjusted by incorporating NC(70)BA into BTR:Y11 binary films. The well-optimized phase separation and molecular arrangement in ternary photoactive layers can well support an enhanced J(SC) and FF for ternary SMPVs. Thus, the photovoltaic performance of SMPVs can be well improved by employing a ternary strategy with NC(70)BA as the third component materials.

Automated summary

The study found that using NC(70)BA as the third component material in inverted small molecule organic photovoltaic devices can achieve higher power conversion efficiency, attributed to the increased photocurrent density, open-circuit voltage, and fill factor. The hollow spherical structure of NC(70)BA helps improve the continuity of electron transport channels, and the optimization of molecular arrangement and crystallinity in the ternary photoactive layer also supports enhanced performance.