TY - GEN
T1 - On the relation between thermal transformations and morphological stability of polymer:fullerene solar cells
AU - Van Assche, Guy
AU - Zhao, Jun
AU - Demir, Fatma
AU - Van Den Brande, Niko
AU - Bertho, Sabine
AU - Vanderzande, Dirk
PY - 2010/5/18
Y1 - 2010/5/18
N2 - High-performance polymer solar cells based on regioregular poly(3-hexyl thiophene) (P3HT, donor) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM, acceptor) represent the current state-of-the-art in organic photovoltaics. Reaching the highest efficiencies for these devices requires an optimum bulk heterojunction morphology, consisting of a co-continuous network with a maximum interface area and a mean domain size of 5-10 nm. Such a morphology can be approached by post-production thermal annealing processes, during which reorganization, aggregation, and further crystallization within the initially amorphous or nanocrystalline deposited films result in the formation of larger well-organized domains. In general, the initial morphology of the deposited blend films is the result of a kinetically frozen phase separation or crystallization. Consequently, both thermodynamic and kinetic parameters are responsible for the morphology obtained. In this contribution, we will present a comprehensive study of the phase behaviour of P3HT/PCBM blends over the whole composition range and compare it to the phase behaviour obtained for other conjugated polymers. These phase diagrams are of key importance to gain a fundamental understanding and control of morphology development in said blends of donor-acceptor materials. Moreover, it should be emphasized that the phase diagram is essential in the understanding of the long-term stability of the blended film morphology and consequently of the photovoltaic performance of the corresponding solar cells. It has in fact been demonstrated that long-term operation of various types of polymer/PCBM solar cells (including P3HT/PCBM) at elevated temperatures results in a significant change of the film morphology and a remarkable decrease of the photovoltaic performance.
In this paper, the use of advanced thermal analysis techniques to obtain the phase diagram for polymer/PCBM blends will be discussed. The use of conventional and modulated temperature differential scanning calorimetry (DSC and MTDSC, respectively), as well as fast-scanning differential scanning calorimetry (RHC) to obtain the transition temperatures and kinetics will be discussed.
AB - High-performance polymer solar cells based on regioregular poly(3-hexyl thiophene) (P3HT, donor) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM, acceptor) represent the current state-of-the-art in organic photovoltaics. Reaching the highest efficiencies for these devices requires an optimum bulk heterojunction morphology, consisting of a co-continuous network with a maximum interface area and a mean domain size of 5-10 nm. Such a morphology can be approached by post-production thermal annealing processes, during which reorganization, aggregation, and further crystallization within the initially amorphous or nanocrystalline deposited films result in the formation of larger well-organized domains. In general, the initial morphology of the deposited blend films is the result of a kinetically frozen phase separation or crystallization. Consequently, both thermodynamic and kinetic parameters are responsible for the morphology obtained. In this contribution, we will present a comprehensive study of the phase behaviour of P3HT/PCBM blends over the whole composition range and compare it to the phase behaviour obtained for other conjugated polymers. These phase diagrams are of key importance to gain a fundamental understanding and control of morphology development in said blends of donor-acceptor materials. Moreover, it should be emphasized that the phase diagram is essential in the understanding of the long-term stability of the blended film morphology and consequently of the photovoltaic performance of the corresponding solar cells. It has in fact been demonstrated that long-term operation of various types of polymer/PCBM solar cells (including P3HT/PCBM) at elevated temperatures results in a significant change of the film morphology and a remarkable decrease of the photovoltaic performance.
In this paper, the use of advanced thermal analysis techniques to obtain the phase diagram for polymer/PCBM blends will be discussed. The use of conventional and modulated temperature differential scanning calorimetry (DSC and MTDSC, respectively), as well as fast-scanning differential scanning calorimetry (RHC) to obtain the transition temperatures and kinetics will be discussed.
KW - solar cells
KW - organic photovoltaics - OPV
KW - conducting polymer
KW - fullerene
KW - modulated temperature DSC - MTDSC
KW - Rapid Heat-Cool DSC - RHC
KW - advanced thermal analysis
KW - phase diagrams
KW - morphology
M3 - Conference paper
SN - 978-3-939473-66-4
SP - 56
EP - 61
BT - Proceedings TPE10 - Technologies for Polymer Electronics, May 18-20 (2010), Rudolstadt, Germany
PB - Thüringisches Institut für Textil- und Kunststoff-Forschung e.V.
T2 - Finds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet
Y2 - 21 September 2009 through 25 September 2009
ER -