Fig. 5: Characteristics of PBDTTPD:PCBM solar cells and hole-only diodes.
a JV curves for different hole collection layers in cell configuration: ITO/20-nm HCL/100-nm PBDTTPD:PCBM (1:1.5 w/w)/30-nm Ca/Al, measured under simulated AM1.5 G irradiance of 100 mW cm−2, spectral mismatch corrected, 298 K. b Cell parameters plotted against work function of hole collection layer. Data give population mean; standard error is smaller than symbol size. Blue lines are guides to the eye for TAF series. Yellow region corresponds to Ohmic regime. c Voc(ϕ, T) plot measured at 1.0 sun. Voc data are averaged for forward and reverse sweeps. Typical uncertainty: ±0.01 V at high ϕ; ±0.05 V at low ϕ. Colored lines are fits with constant slope of 80 mV eV‒1. The black line (\(\frac{{{d}V_{{\mathrm{oc}}}}}{{{d}\phi }}\) = 1) is anchored by low-temperature data set for ϕ = 5.2 eV. Below 50 K, Voc approaches Vo, which is the low-temperature Vbi. d Plot of effective hole mobility against work function of hole injection layer in hole-only diodes: ITO/20-nm HIL/100─120-nm PBDTTPD:PCBM (1:1.5 w/w)/Ag, for TAF series (circles) and PEDT:PSSH (square) as HIL. Error bar corresponds to standard error of mean. Green dashed line is from Gaussian disorder theory (see text).
