Fig. 5

Steepening the absorption edge for reduced photon energy losses with strong coupling. a Sensitively measured EQE spectra of the investigated SubNc/Cl₆-PhOSubPc based SC-devices for various transport layer thicknesses d, including the reference solar cell employing only SubNc (‘SubNc’). Increasing d red-shifts the device absorption, steepening the absorption edge. b Urbach energy (E_U) versus E_g–qV_OC losses for the SubNc/Cl₆-PhOSubPc based SC-device (‘SC-SubNc’), exhibiting the E_U = 15.6 meV and energy losses of 0.525 eV, and record solar cells of other inorganic photovoltaic technologies. The reference SubNc/Cl₆-PhOSubPc device (‘SubNc’) is also included to demonstrate how strong coupling reduces both E_U and photon energy losses. Adapted by De Wolf et al. ³³ and Jean et al. ³⁶. c E_U values for various organic photovoltaic materials and blends. The value of 15.6 meV for the ‘SC-SubNc’ device is the lowest for organic materials. Values of materials and blends, which were not investigated in this work, were taken from literature^{34,37,38,39,40}