EN
Herein we demonstrate a method to improve the power conversion
efficiency (PCE) parameter of organic photovoltaic
(OPV) devices based on the electron acceptor N,N’-bis(1-
ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI)
blended with the electron donor poly(indenofluorene)-aryloctyl
(PIF-Aryl). The device parameters of the short-circuit
current, open-circuit voltage and fill factor are found increased
after the insertion of a thin poly [9, 9-dioctylfluorene-co-N-
[4-(3-methylpropyl)]-diphenylamine] (TFB) photoactive interlayer
between the hole-collecting electrode and the photoactive
layer of the device. Unlike to most of the cases where
interlayers serve as charge extractors, in our system the polymeric
interlayer serves as a morphology modifying agent that
drives the PDI component to segregate better at the interface
with the device cathode; that is at the carrier-collecting electrode
interface, which is not in physical contact with the interlayer.
The processes of energy/charge transfer of the TFB excitons
to/with the PIF-Aryl:PDI top-layer are also addressed.
Charge transfer reactions dominate at the TFB/PIF-Aryl:PDI
interface but no significant contribution in the photocurrent
generation is seen in the photoaction spectra of the bilayer
device.