(a,b) I-V characteristics under dark (blue dots) and AM1.5G illuminated conditions (red dots) of (a) the unpassivated and (b) passivated SNWSCs with the highest efficiency. The black line is a fit to the data. Passivation increased the efficiency by 50%. (c) A scanning electron microscope image of the best passivated device. Scale bar, 1 μm. (d) P–V comparison between the best passivated (Pmax=10.2 mW cm−2) (red) and unpassivated (Pmax=6.8 mW cm−2) (blue) SNWSC. (e) Histogram of the 1-sun efficiency of 28 unpassivated (blue) and 43 passivated (red) SNWSCs. The Lorentzian fit shows that the passivation has increased the average efficiency by 72% (5.0% for the passivated versus 2.9% for the unpassivated). (f) External quantum efficiency (EQE) versus photon energy of the SNWSC in b,c.