Fig. 4: Performance optimization.
From: N-type and P-type series integrated hydrogel thermoelectric cells for low-grade heat harvesting
a Output current and voltage of hydrogel i-TECs with KCl addition. b Couple of N-type and P-type i-TECs. c Voltage–current–power. d Maximum power density (Pmax) and normalized instantaneous power density (Pmax/ΔT2). e Comparison of the S and Pmax/ΔT2. The literature and data represented by letters (a–h) are listed in Table S1. f Comparison of the S and Carnot-relative efficiency (ηr). The error bars were calculated using the standard deviation of the measured value.
