Effect of temperature, humidity and pressure on electric properties of the cells based on PTB7-Th, PC61BM and graphene composite

In this paper, fabrication and characterization of Cu/PTB7-Th (35 mass%)/PC $$_{61}$$ BM (35 mass%)/graphene (30 mass%)/Ag thin-film composite cells are given. First of all, Ag and Cu electrodes were deposited on flat glass substrate by vacuum evaporation with 130- $$\upmu $$ m inter-electrode gap. The PTB7-Th (35 mass%) composite and PC $$_{61}$$ BM (35 mass%) composite in chlorobenzene and graphene (30 mass%) were deposited on the inter-electrode gap by drop-casting technique, and film thickness of 8–12 $$\upmu $$ m was achieved. The dependence of forward and reverse bias resistance of the cells versus temperature in the range of 25–75 $${^{\circ }}$$ C, humidity in the range of 47–90 %RH and pressure in the range of 0–7.7 kN m $$^{-2}$$ was measured. The average temperature resistance coefficients were equal to (− 1.03)% $${^{\circ }}\hbox {C}^{-1}$$ and $$(-\,1.14)\%\ {^{\circ }}\hbox {C}^{-1}$$ for forward and reverse bias resistances, respectively. The reverse and forward bias resistances decreased 1.29 and 1.27 times due to $$\%\mathrm{RH}$$ , and due to pressure, it decreased by 9.0–9.2%. Impedance (Z) of the sample was also measured at different frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz) which decreased from 1.23 to 1.04 times. The obtained results are explained, firstly, by transfer of charges between donors and acceptors molecules and effect of water molecules on the PTB7-Th (35 mass%):PC $$_{61}$$ BM (35 mass%):graphene composite.