Imperial College London


Faculty of Natural SciencesDepartment of Chemistry

Research Associate







G22Molecular Sciences Research HubWhite City Campus






BibTex format

author = {Cha, H and Wu, J and Wadsworth, A and Nagitta, J and Limbu, S and Pont, S and Li, Z and Searle, J and Wyatt, MF and Baran, D and Kim, J-S and McCulloch, I and Durrant, JR},
doi = {10.1002/adma.201701156},
journal = {Advanced Materials},
title = {An efficient, "burn in" free organic solar cell employing a nonfullerene electron acceptor},
url = {},
volume = {29},
year = {2017}

RIS format (EndNote, RefMan)

AB - A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'″-di(2-octyldodecyl)-2,2';5',2″;5″,2'″-quaterthiophen-5,5'″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC71 BM solar cells show significant efficiency loss under simulated solar irradiation ("burn in" degradation) due to the trap-assisted recombination through increased photoinduced trap states, PffBT4T-2OD:EH-IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T-2OD:EH-IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T-2OD:PC71 BM devices.
AU - Cha,H
AU - Wu,J
AU - Wadsworth,A
AU - Nagitta,J
AU - Limbu,S
AU - Pont,S
AU - Li,Z
AU - Searle,J
AU - Wyatt,MF
AU - Baran,D
AU - Kim,J-S
AU - McCulloch,I
AU - Durrant,JR
DO - 10.1002/adma.201701156
PY - 2017///
SN - 0935-9648
TI - An efficient, "burn in" free organic solar cell employing a nonfullerene electron acceptor
T2 - Advanced Materials
UR -
UR -
UR -
VL - 29
ER -