Fig. 6: Device performance as a function of materials, electrolyte, and environmental conditions (Heat/Light).
a Schematic representation of the device measurement configuration with various external loads for different surface temperatures and under illumination. The measurements were conducted at ambient temperature with or without solar illumination or elevated surface temperature. b Power-load resistance profiles for various conditions (ambient: Ts = 25 °C; 1 Sun: 1 kW/m2 solar intensity and Ts = 25 °C; heat: TS = 70 °C) at 1 mM and 100 mM KCl. The profiles demonstrate an increase in peak and a shift of the toward lower resistances under illumination and at elevated temperatures. The empty (crossed) circles represent experimental values, while the solid (dashed) lines illustrate fits based on our model for 1 mM (100 mM) KCl; c Power-load resistance profiles for various surface temperatures (Ts) at 1 mM KCl demonstrate an increase in peak height and a shift in the peak toward lower resistance at elevated temperatures. The empty circles represent experimental data, while the solid lines show the model fit (fitting parameters in S26). d Steady-state open circuit voltage values for two devices with Al2O3 and TiO2 dielectric shell but with the same silicon core (Low N-doped: 1–20 Ω.cm) at different salinity values. The blue and orange circle is measured at a surface temperature of Ts = Tambient = 25 °C and Ts = TH = 70 °C, respectively. e Long-term stability testing of the device. The open circuit voltage was measured for 45 h using an Ag/AgCl electrode. We illuminated the sample with light (solar spectrum, 100 mW/cm²) in 1-h on and off cycles for a total duration of around 15 h. The inset provides an enlarged view of the regions marked in purple and pink rectangles. The region marked in purple shows an enlarged light off-on-off cycle, clearly showing the instantaneous response of the Voc to illumination, which demonstrates photocharging rather than photothermal effects. The region marked in red shows stability of the measurement, with less than 2 mV change in 2 h. f Open circuit voltage, g Power density at different salt concentrations for various EDHV devices.
