Stability study of high efficiency polymer solar cells using TiOx as electron transport layer

Sánchez, José G.; Balderrama, Víctor S.; Estrada, M.; Osorio, Edith; Ferré‐Borrull, Josep; Marsal, Lluís F.; Pallarès, Josep

doi:10.1016/j.solener.2017.04.013

Cited by 45 publications

(23 citation statements)

References 39 publications

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“…8 ). The improved stability of the doped samples can be partly explained by the fact that H dopants terminate dangling bonds preventing adsorption of oxygen and moisture on the TiO 2 surface 47 . Note that the devices were intentionally un-encapsulated so that they were exposed to ambient conditions (moisture and oxygen) throughout the aging study.…”

Section: Resultsmentioning

confidence: 99%

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Vasilopoulou

Kelaidis

Polydorou

et al. 2017

Sci Rep

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TiO 2 has high chemical stability, strong catalytic activity and is an electron transport material in organic solar cells. However, the presence of trap states near the band edges of TiO 2 arising from defects at grain boundaries significantly affects the efficiency of organic solar cells. To become an efficient electron transport material for organic photovoltaics and related devices, such as perovskite solar cells and photocatalytic devices, it is important to tailor its band edges via doping. Nitrogen p-type doping has attracted considerable attention in enhancing the photocatalytic efficiency of TiO 2 under visible light irradiation while hydrogen n-type doping increases its electron conductivity. DFT calculations in TiO 2 provide evidence that nitrogen and hydrogen can be incorporated in interstitial sites and possibly form N i H i , N i H O and N Ti H i defects. The experimental results indicate that N i H i defects are most likely formed and these defects do not introduce deep level states. Furthermore, we show that the efficiency of P3HT:IC 60 BA-based organic photovoltaic devices is enhanced when using hydrogen-doping and nitrogen/hydrogen codoping of TiO 2 , both boosting the material n-type conductivity, with maximum power conversion efficiency reaching values of 6.51% and 6.58%, respectively, which are much higher than those of the cells with the as-deposited (4.87%) and nitrogen-doped TiO 2 (4.46%).Metal oxides such as titanium dioxide (TiO 2 ) have been intensively investigated for more than four decades because of their strong catalytic activity, high chemical stability and long lifetime of photon generated carriers [1][2][3][4][5][6][7][8][9][10] . Anatase exhibits the highest photocatalytic activity of the polymorphs of TiO 2 , however, it is constrained to the limited ultraviolet range (UV irradiation is only 5%) of the solar spectrum due to its large band gap (3.2eV) 7 . For a photocatalyst to achieve high efficiency, its band gap should be around 2.0 eV, whereas the position of the band edges should be consistent with the redox potential of water 11 . A way to reduce the band gap is doping, with nitrogen (N) atom being a particularly promising p-type dopant 3,12 .Hydrogen (H) is a small atom so it can diffuse easily in inorganic compounds occupying interstitial sites. It does not induce significant structural expansion, can modify the band gap, enhance the photocatalytic activity 13 , induce insulator-to-conductor transitions 14 , provide free electrons 15 , and interact with intrinsic defects such as oxygen vacancies 16 . H can be introduced in TiO 2 during synthesis or by immersion in water 12 . Interestingly, previous theoretical studies have shown that hydrogen can substitute for oxygen (termed as substitutional H, H O ) leading to n-type conductivity 17,18 . H doping has recently been established as an effective strategy for improving the capacitive properties of TiO 2 for application in supercapacitors 19 . Additionally, the emergence of a highly H doped TiO 2 (black titania) nanomateri...

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Section: Resultsmentioning

confidence: 99%

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Vasilopoulou

Kelaidis

Polydorou

et al. 2017

Sci Rep

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“…To circumvent the above problem, the PSCs with an inverted structure, which use air stable n-type metal oxides zinc oxide (ZnO) or titanium oxide (TiO X ) as the electron transport layers (ETLs), have been invented. [16,17] ZnO has been the most extensively studied material for ETLs of inverted PSCs in view of its relatively high electron mobility, optical transparency, ease of being synthesized with low cost solution methods at low temperature, versatile morphologies, and being environmentally stable. [18] Over the past years, there are a lot of work focusing on the fabrication and characterization of ETLs with pristine ZnO, [19] doped-ZnO, [20] and ZnO-based composites [21] and the surface modification of ZnO-based ETLs.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, ITO anode can be corroded by the hygroscopic and acidic PEDOT: PSS, resulting in the degradation of device performance. To circumvent the above problem, the PSCs with an inverted structure, which use air stable n‐type metal oxides zinc oxide (ZnO) or titanium oxide (TiO X ) as the electron transport layers (ETLs), have been invented ,…”

Section: Introductionmentioning

confidence: 99%

Effect of Crystallinity Modulation between Electron Transport Layer and Photo‐Generation Materials on ZnO‐Based Polymer Solar Cells

et al. 2018

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As one of the most widely used electron transport layers (ETLs) for inverted polymer solar cells (PSCs), ZnO has great effect on the growth of photo‐generated layer. In this work, the ZnO‐based PSCs with the compositional blend of PffBT4T‐2OD: PCBM and PTB7‐Th: PCBM are fabricated to investigate the crystallinity modulation effect (CME) between electron transport layer and photo‐generation materials. The results showed that both the high crystallinity PffBT4T‐2OD: PCBM processed on the large nanoparticles ZnO and the low crystallinity PTB7‐Th: PCBM processed on small nanoparticles ZnO exhibit excellent photovoltaic performances. By verifying the combination of ZnO nanoparticles with photo‐generation materials, it proves that the CME can result in a smooth photo‐generated layer surface to ensure efficient electron transport as well as collection with suppressed bimolecular recombination, leading to the increase of photocurrent and the improvement of inverted PSCs performance accordingly.

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“…However, the strongly oxidizing properties of Ca and the hygroscopic nature of PEDOT:PSS limit the performance and lifetime of PSCs [9]- [12]. Therefore, the Ca is replaced by titanium oxide (TiO x ) [13]- [15], zinc oxide (ZnO) [16], [17], and the poly[(9,9-bis(3-(N,N-dimethylamino) propyl)-2,7-fluorene)alt-2,7-(9,9 dioctylfluorene)] (PFN) [18], [19], as electron transporting layer (ETL) due to their high transparency as thin films and good electron mobility, moreover they can modify the surface of indium tin oxide (ITO) in order to improve the electron collection efficiency. Therefore, PEDOT:PSS is mainly replaced by metal oxides such as molybdenum oxide (MoO 3 ), nickel oxide (NiO), or vanadium oxide (V 2 O 5 ) since they can provide a low resistance ohmic at the HTL/bulk interface and increase the stability of devices [20].…”

Section: Introductionmentioning

confidence: 99%

“…Organic solar cells based on electron-donating polymers and electron-accepting fullerenes with high efficiencies, e.g., PTB7:PC 70 BM [13], [18], PTB7-Th:PC 70 BM [14], [19], [21], has been reported. Although encouraging efficiencies have been obtained with PSCs based on polymer-fullerene [19], [21], the performance of devices is limited by fullerenes properties such as weak light absorption in the visible region, poor ambient stability, monotonous tunability of molecular energy levels, and a high electron affinity which limits the V OC of the devices [22].…”

Section: Introductionmentioning

confidence: 99%

Effects of Annealing Temperature on the Performance of Organic Solar Cells Based on Polymer: Non-Fullerene Using V₂O₅ as HTL

Sánchez

Torimtubun

Balderrama

et al. 2020

IEEE J. Electron Devices Soc.

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The annealing temperature and thickness are two important factors to optimize the morphology of the active layer for a better performance of inverted polymer solar cells (iPSCs). Herein, the effects of the annealing temperature and the thickness of the active layer on the performances of iPSCs based on PBDB-T:IT-M are analyzed. Titanium oxide and vanadium oxide are used as electron and hole transporting layers, respectively. The device made with PBDB-T:IT-M layer (ca. 90 nm thick) thermally annealed at 100 • C exhibits the best performing under simulated AM 1.5G light. The idealities factor of iPSCs with two different annealing temperatures are determined by measuring the open-circuit voltage as a function of light intensity. The study shows that recombination losses in iPSCs annealed at 160 • C are governed by non-geminate recombination mechanisms, while in iPSCs annealed at 100 • C, the recombination losses are mainly due to band-tail trap states. Additional impedance spectroscopy measurements reveal that the device with an annealing temperature of 160 • C exhibits a higher charge-transfer in the bulk layer. However, the device thermally annealed at 100 • C shows lower charge-transfer resistance through all layers involved in the charge extraction. The results of this work show the importance of the annealing temperature on the charge-transfer at the active layer/vanadium oxide interface.

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Stability study of high efficiency polymer solar cells using TiOx as electron transport layer

Cited by 45 publications

References 39 publications

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Effect of Crystallinity Modulation between Electron Transport Layer and Photo‐Generation Materials on ZnO‐Based Polymer Solar Cells

Effects of Annealing Temperature on the Performance of Organic Solar Cells Based on Polymer: Non-Fullerene Using V₂O₅ as HTL

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Stability study of high efficiency polymer solar cells using TiOx as electron transport layer

Cited by 45 publications

References 39 publications

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Hydrogen and nitrogen codoping of anatase TiO2 for efficiency enhancement in organic solar cells

Effect of Crystallinity Modulation between Electron Transport Layer and Photo‐Generation Materials on ZnO‐Based Polymer Solar Cells

Effects of Annealing Temperature on the Performance of Organic Solar Cells Based on Polymer: Non-Fullerene Using V2O5 as HTL

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Effects of Annealing Temperature on the Performance of Organic Solar Cells Based on Polymer: Non-Fullerene Using V₂O₅ as HTL