The Critical Role of Processing and Morphology in Determining Degradation Rates in Polymer Solar Cells

Kumar, Ankit; Hong, Ziruo; Sista, Srinivas; Yang, Yang

doi:10.1002/aenm.201000030

Cited by 38 publications

(28 citation statements)

References 45 publications

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“…[117] The influence of different processing parameters on the morphological stability have been studied by Kumar et al who found that P3HT:PCBM films spin-coated with added 1,8-octanedithiol degraded much faster than films made from other solvents. [118] The temperature used to dry the active layer film may also affect both efficiency and stability as shown by Lin et al [119] If the active layer film is dried at -5 °C compared to RT the efficiency increased from 3.23 to 4.70% and a storage half-life increased from 143 h to 1250 h. Also the regio-regularity of the P3HT seems to have a large effect. In a study with two regio-regularities of 94% and 98% Ebadian et al showed that the devices based on the high regio-regular P3HT lost efficiency much faster than those based on the low regio-regular material.…”

Section: The Active Layermentioning

confidence: 93%

Stability of Polymer Solar Cells

et al. 2011

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Organic photovoltaics (OPVs) evolve in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) has in the last decade been increased by almost a factor of ten approaching 10%. A main concern has been the stability that was previously measured in minutes, but can now, in favorable circumstances, exceed many thousands of hours. This astonishing achievement is the subject of this article, which reviews the developments in stability/degradation of OPVs in the last five years. This progress has been gained by several developments, such as inverted device structures of the bulk heterojunction geometry device, which allows for more stable metal electrodes, the choice of more photostable active materials, the introduction of interfacial layers, and roll-to-roll fabrication, which promises fast and cheap production methods while creating its own challenges in terms of stability.

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Section: The Active Layermentioning

confidence: 93%

Stability of Polymer Solar Cells

et al. 2011

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“…In some organic photovoltaic (OPV) devices, thermal annealing is an important approach to tune the nanoscale morphology of the active layer to improve device efficiency . This is commonly observed in OPVs made of semi‐crystalline conjugated polymers as electron donors, for example, P3HT, poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b] thiophene) (PBTTT) and so on .…”

Section: Surface and Interface Modified Thermal Properties In Polymermentioning

confidence: 99%

Surface and Interface Modified Thermal, Structural and Charge Transport Properties in Conjugated Polymer Thin Films

Hui

Liu

Wang

2016

Adv Materials Inter

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place within the active layer during device operation. They can also be employed as the active layer in electronic devices, for instance fi eld effect transistors (FETs), [10][11][12][13] where the gate voltage mediates the charge transport in the channel from source to drain of a transistor.In these devices, the layer made of conjugated polymer usually has a thickness of tens to hundreds of nanometers, and is necessarily interfaced with other layers with specifi c functions to make an operational device. These functional layers can be made from a range of materials, for example, small molecules, polymers, metals or metal oxides. [ 14,15 ] It is well accepted that the free surface and interface effects can signifi cantly infl uence the physical properties of many materials under confi nement. [16][17][18][19] The proximity of conjugated polymer thin fi lms to the aforementioned materials can affect the molecular conformation and orientation, therefore impacts on the physical properties near the interfacial region through to the bulk, and consequently infl uences the electronic and optoelectronic properties of devices. [19][20][21] An overview of fundamental characters of nanometer-thick conjugated polymer thin fi lms interfacing different materials, and the consequent infl uences on their thermal, structural and charge transport properties, is overdue and falls in the focus of this article. We start with the deviations of the glass transition temperature (T g ) of saturated polymer thin fi lms from their bulk values and discuss how free surface and interfacial inter actions will change chain dynamics and impact on the local T g at different depth and consequently the averaged T g of the whole thin fi lm. We then summarize the deviations of thermal transition temperatures, i.e. T g and crystallization temperature (T c ), of conjugated polymer thin fi lms supported on different substrates. Characteristics of molecular structure, i.e. π−π stacking, orientation and crystallinity, in the cross-section of conjugated polymer thin fi lms as probed by surface-and depth-sensitive techniques like near-edge X-ray absorption fi ne structure (NEXAFS) and grazing incidence wide angle X-ray scattering (GIWAXS) are summarized. The infl uences of local molecular structure at different depth of a thin fi lm on the out-of-plane and in-plane charge mobilities of conjugated polymers in diode and fi eld-effect transistor devices are also discussed.Conjugated polymers are widely employed as the active layer in various electronic and optoelectronic devices. In this article, the modifi cations of thermal, structural and charge transport properties of conjugated polymers confi ned in thin fi lm geometry are reviewed. Deviations of thermal transition temperatures of conjugated polymers are summarized and discussed through lessons drawn from conventional saturated polymer thin fi lms. These phenomena are explained by the surface and interface effects that virtually divide a thin fi lm into several vertically heterogeneous layers each having ...

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“…The factors limiting stability of OSCs include light, oxygen, and humidity . By encapsulation, the effect of oxygen and humidity could be mostly suppressed while the unavoidable light and accumulated heat from illumination may degrade the performance seriously .…”

Section: Introductionmentioning

confidence: 99%

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

Yin

Zhou

Zhang

et al. 2017

Macromol. Rapid Commun.

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The halogen-free solvent additive, 1,4-butanedithiol (BT) has been incorporated into PTB7-Th:PC BM, leading to higher power conversion efficiency (PCE) value as well as substantially enhanced thermal stability, as compared with the traditional 1,8-diiodooctane (DIO) additive. More importantly, the improved thermal stability after processing with BT contributes to a higher glass transition temperature (T ) of PTB7-Th, as determined by dynamic mechanical analysis. After thermal annealing at 130 °C in nitrogen atmosphere for 30 min, the PCE of the specimen processed with BT reduces from 9.3% to 7.1%, approaching to 80% of its original value. In contrast, the PCE of specimens processed with DIO seriously depresses from 8.3% to 3.8%. These findings demonstrate that smart utilization of low-boiling-point solvent additive is an effective and practical strategy to overcome thermal instability of organic solar cells via enhancing the T of donor polymer.

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The Critical Role of Processing and Morphology in Determining Degradation Rates in Polymer Solar Cells

Cited by 38 publications

References 45 publications

Stability of Polymer Solar Cells

Stability of Polymer Solar Cells

Surface and Interface Modified Thermal, Structural and Charge Transport Properties in Conjugated Polymer Thin Films

Improved Glass Transition Temperature towards Thermal Stability via Thiols Solvent Additive versus DIO in Polymer Solar Cells

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