Fig. 1

(a) Device structure schematic and energy alignment of the layers employed in the inverted devices (b) J–V characteristics of the devices with and without sodium caseinate (c) external quantum efficiency (EQE) of the devices (left) and integrated photocurrent (right) (d) normalized PCE results obtained from long term stability tests (e) PV performance statistics for eleven devices fabricated with either pristine or sodium caseinate doped BCP layers.