Fig. 4: The advantage of using the leaf and high-performance power output of LEH.
a I-V curves of energy harvester devices with different substrates. The LEH delivered the highest Isc among others. b Voc (black line) and Isc (red line) as a function of the substrate’s electrical conductivity (Error bars: Three-time measurements). c CB loading content on LEH and plastic under the same dip-coating cycles. The low CB loading content on the plastic is due to its hydrophobic nature. d Electrical conductivity of the substrates under different CB loadings (Device number: 9). LEH endowed the highest electrical conductivity under the same CB loading content among other substrates. The electrical conductivity of PVA films could reach the same level as that of LEH only under very low CB loading content. e–h SEM images of e the white leaf, f the filter paper, g the fabric, and h the PVA film. A rough and rugged surface could be viewed on the surface of the fabric and filter paper, while the PVA film had a very flat surface. The white leaf exhibited its specific cell structures with small grooves. Inset: photos of different substrates. i–l AFM images of i the white leaf, j the filter paper, k the fabric, and l the PVA film with roughly the same CB loading density. m Surface roughness of the white and conductive substrates calculated through profilometer measurements. (Device Number: 11, Note that the CB loading densities of different substrates were roughly the same at around 15 g/m2). n Measured Voc, Isc, and power output of LEH under different external resistances.
