Premium
Bilayer–Ternary Polymer Solar Cells Fabricated Using Spontaneous Spreading on Water
Author(s) -
Colberts Fallon J. M.,
Wienk Martijn M.,
Heuvel Ruurd,
Li Weiwei,
Le Corre Vincent M.,
Koster L. Jan Anton,
Janssen René A. J.
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201802197
Subject(s) - materials science , ternary operation , bilayer , polymer solar cell , band gap , optoelectronics , fullerene , organic solar cell , polymer , energy conversion efficiency , heterojunction , active layer , layer (electronics) , nanotechnology , composite material , membrane , organic chemistry , chemistry , genetics , thin film transistor , computer science , biology , programming language
Abstract A new method is presented to fabricate bilayer organic solar cells via sequential deposition of bulk‐heterojunction layers obtained using spontaneous spreading of polymer–fullerene blends on a water surface. Using two layers of a small bandgap diketopyrrolopyrrole polymer–fullerene blend, a small improvement in power conversion efficiency (PCE) from 4.9% to 5.1% is obtained compared to spin‐coated devices of similar thickness. Next, bilayer–ternary cells are fabricated by first spin coating a wide bandgap thiophene polymer–fullerene blend, followed by depositing a small bandgap diketopyrrolopyrrole polymer–fullerene layer by transfer from a water surface. These novel bilayer–ternary devices feature a PCE of 5.9%, higher than that of the individual layers. Remarkable, external quantum efficiencies (EQEs) over 100% are measured for the wide bandgap layer under near‐infrared bias light illumination. Drift‐diffusion calculations confirm that near‐infrared bias illumination can result in a significant increase in EQE as a result of a change in the internal electric field in the device, but cannot yet account for the magnitude of the effect. The experimental results indicate that the high EQEs over 100% under bias illumination are related to a barrier for electron transport over the interface between the two blends.