Imperial College London


Faculty of Natural SciencesDepartment of Chemistry

Professor of Photochemistry



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Miss Lisa Benbow +44 (0)20 7594 5883




G22CMolecular Sciences Research HubWhite City Campus






BibTex format

author = {Kim, J-S},
doi = {10.1002/admi.201801763},
journal = {Advanced Materials Interfaces},
title = {Impact of initial bulk-heterojunction morphology on operational stability of polymer:fullerene photovoltaic cells},
url = {},
volume = {6},
year = {2019}

RIS format (EndNote, RefMan)

AB - Controlling initial bulk-heterojunction (BHJ) morphology is critical for device performance of organic photovoltaic (OPV) cells. However, its impact on performance, specifically long-term operational stability is still poorly understood. This is mainly due to limitations in direct measurements enabling in-situ monitoring of devices at a molecular level. Here, we utilize thermal annealing preconditioning step to tune initial morphology of model polymer:fullerene BHJ OPV devices and molecular resonant vibrational spectroscopy to identify in-situ degradation pathways. We report direct spectroscopic evidence for molecular-scale phase segregation temperature (TPS) which critically determines a boundary in high efficiency and long operational stability. Under operation, initially well-mixed blend morphology (no annealing) shows interface instability related to the hole-extracting PEDOT:PSS layer via de-doping. Likewise, initially phase-segregatedmorphology at a molecular level (annealed above TPS) shows instability in the photoactive layer via continuous phase segregation between polymer and fullerenes in macroscales, coupled with further fullerene photodegradation. Our results confirm that a thermal annealing preconditioning step is essential to stabilize the BHJ morphology; in particular annealing below TPS is critical for improved operational stability whilst maintaining high efficiency.
AU - Kim,J-S
DO - 10.1002/admi.201801763
PY - 2019///
SN - 2196-7350
TI - Impact of initial bulk-heterojunction morphology on operational stability of polymer:fullerene photovoltaic cells
T2 - Advanced Materials Interfaces
UR -
UR -
VL - 6
ER -