JV curves taken at AM 1.5G one-sun (100 mW/cm2) illumination conditions of inverted P3HT:PCBM BHJ solar cells with different active layer thicknesses: 100 nm (blue squares), 190 nm (red triangles), and 400 nm (green circles). (Inset) Schematic of the inverted device structure.
(a) Experimental schematic of white-light biased external quantum efficiency measurement with monochromatic light of wavelength from 350 nm and 750 nm. (b) Schematic of optical excitation under white-light biased conditions, where a monochromatic intensity perturbation probes differential current generation under continuous white-light illumination. (c) Illustration of differential current as a function of white-light intensity for the case where spectral responsivity is linear (black) and sub-linear (red) in intensity.
(a) Spectral mismatch corrected JLID (λ) and J* (λ) of the d = 400 nm devices measured in the white-light biased EQE with background intensity of one sun. (b) Jsc vs. light intensity as measured at V = 0 V from JV measurements (Jsc (JV), black circles), via lock-in detection (JLID , red squares), and integrated lock-in signal (J* , blue triangles) for the d = 400 nm device.
The EQE* and JV spectra taken under different intensities of white-light bias on inverted P3HT:PCBM devices with active layer thickness of (a) and (b) 100 nm, (c) and (d) 190 nm, and (e) and (f) 400 nm. Background light intensities are 1 mW/cm2 (light purple right-facing triangles), 3 mW/cm2 (dark purple left-facing triangles), 6 mW/cm2 (blue upside down triangles), 10 mW/cm2 (green triangles), 30 mW/cm2 (yellow circles), 60 mW/cm2 (orange diamonds), and 100 mW/cm2 (redsquares). In all, lines are guides to the eye, JV data shown in (b), (d), (f) are a subset of a larger set of data taken, abbreviated here for clarity and shown in full in Figure S2.
Light-intensity dependent αEQE * as derived from EQE measurements for the P3HT:PCBM BHJ inverted architecture devices with active layer thicknesses, d = 100 nm (blue squares), d = 190 nm (red triangles), and d = 400 nm (green circles).
(a) αEQE * plotted versus intensity-dependent fill factor extracted from JV for the d = 400 nm P3HT:PCBM BHJ inverted architecture device; (b) Voltage-dependent αJV extracted from JV measurements (power law fit to data from 30 to 100 mW/cm2 illumination intensity).
Wavelength dependence of αEQE * between 350 to 750 nm at 100 mW/cm2 illumination intensity (triangles) for (a) 400-nm active layer inverted devices and (b) 350-nm active layer conventional devices. The solid blacklinerepresents αEQE * calculated from J*, i.e., full-spectrum value. Inset: Exciton generation rate profiles calculated using TMM in the active layer for (a) 450–600 nm wavelength regime (green diamonds) and 600–750 nm regime (red) in the inverted device structure, and (b) 450–570 nm wavelength regime (green) and 570–750 nm regime (red circles) for 350-nm thick conventional devices. 0 nm in the position represents the interface between the front contact (ZnO in (a) and PEDOT in (b)) and the active layer, and maximum position represents interface between the active layer and the back contact (PEDOT in (a) and Cain (b)).
Device parameters of inverted OPV devices with different P3HT:PCBM BHJ active layer thickness taken under AM 1.5G one-sun (100 mW/cm2) illumination conditions using a solar simulator. The series resistances for all devices are the same, 9±1 Ω cm2.
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