In-depth investigation of the charge extraction efficiency for thermally annealed inverted bulk-heterojunction solar cells

Kolb, Florian; Busby, Yan; Houssiau, Laurent; List‐Kratochvil, Emil J. W.

doi:10.1063/1.5052409

Cited by 3 publications

(3 citation statements)

References 58 publications

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“…One possible method to quantify the depth of damaged material is based on the use of an alternative, nondetrimental sputtering technique utilizing gas cluster ion beams (GCIB) or molecular clusters. Such gentler sputtering techniques were first explored in combination with secondary ion mass spectrometry (SIMS) − but more recently have also been employed in combination with XPS, , allowing for an essentially damage-free depth profiling of organic materials. , For example, in the case of PEDOT:PSS films, Yun et al have shown that while monatomic Ar + etching alters the bonding states of C, S, and O, changing the chemical composition of the bulk material, argon cluster etching preserves the PEDOT:PSS core level structure …”

Section: Introductionmentioning

confidence: 99%

Quantifying the Damage Induced by X-ray Photoelectron Spectroscopy Depth Profiling of Organic Conjugated Polymers

Hofstetter

Vaynzof

2019

ACS Appl. Polym. Mater.

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X-ray photoemission spectroscopy (XPS) depth profiling using monoatomic Ar + ion etching sources is a common technique that allows for the probing of the vertical compositional profiles of a wide range of materials. In polymer-based organic photovoltaic devices, it is commonly used to study compositional variations across the interfaces of the organic active layer with charge extraction layers or electrodes, as well as the vertical phase separation within the bulkheterojunction active layer. It is generally considered that the damage induced by the etching of organic layers is limited to the very top surface, such that the XPS signal (acquired from the top ~10 nm of the layer) remains largely unaffected, allowing for a reliable measurement of the sample composition throughout the depth profile. Herein, we investigate a range of conjugated polymers 2 and quantify the depth of the damage induced by monoatomic etching for Ar + ion energies ranging from 0.5 keV to 4 keV using argon gas cluster ion beam depth profiling. The results demonstrate that even when etching with the lowest available monoatomic ion energy for as little as 3 s, the damaged polymer material extends deeper into the bulk than the XPS probing depth. We show that the damaged material distorts the compositional information obtained by XPS, resulting in erroneous depth profiles. Furthermore, we propose that only gas cluster ion beam etching sources should be used for depth profiling of organic conjugated polymers, as those induce significantly less damage and maintain the compositional information throughout the entire profile.

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Section: Introductionmentioning

confidence: 99%

Quantifying the Damage Induced by X-ray Photoelectron Spectroscopy Depth Profiling of Organic Conjugated Polymers

Hofstetter

Vaynzof

2019

ACS Appl. Polym. Mater.

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“…It is worth mentioning that in the case of the evaporation of MoO 3 onto polymers, differences in the sticking coefficient of Mo and O have been discussed …”

Section: Resultsmentioning

confidence: 99%

“…It is worth mentioning that in the case of the evaporation of MoO 3 onto polymers, differences in the sticking coefficient of Mo and O have been discussed. 27 NaF-Modified Organic Films at 0°Angle of Observation. The photoelectron peak positions and the relative intensities for a range of NaF depositions on PCBM and P3HT are shown in Table 1.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

On the Growth of Evaporated NaF on Phenyl-C61-butyric Acid Methyl Ester and Poly(3-hexylthiophene)

Schmerl

Andersson

2020

J. Phys. Chem. C

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NaF has been considered as a material for the electron extraction layer in organic photovoltaic devices. Thin layers of NaF were evaporated onto phenyl-C61-butyric acid methyl ester and poly(3-hexylthiophene) thin films. The chemical state of NaF was observed for various layer thicknesses via X-ray photoelectron spectroscopy (XPS) for a very low deposition (∼1 Å) layer, a thick 30 Å layer, and also for sequential depositions of the salt. The chemical states were also mapped at different surface depths via angle-resolved XPS measurements. NaF was not found to dissociate; however, an extra chemical state in fluorine was observed on all samples and it is suspected that incidental nonstoichiometric clusters were deposited along with the expected NaF monomer units. The electronic properties of the valence band were determined via UV-photoelectron spectroscopy and metastable-induced electron spectroscopy for a range of thicknesses with the sequential depositions up to a nominal value of 30 Å NaF. The interfacial dipole was investigated and was seen to be affected by the deposition method of the salt and also by the salt layer thickness. Concentration depth profiles were obtained via neutral impact collision ion scattering spectroscopy, and it is believed that the salt layer forms islands with some diffusion.

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Fabrication of bulk heterojunction organic solar cells with different configurations using electrospray

Shah

2020

Nano Ex.

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In this work, we fabricated bulk heterojunction (BHJ) organic solar cells (OSCs) using electrospray deposition (ESD) with two different device configurations. ITO/PEDOT:PSS/P3HT: PCBM/Ca/Al and ITO/ZnO and TiO2/P3HT: PCBM/MoO3/Ag, termed as direct and inverted OSCs, respectively. In ZnO/ TiO2 -based inverted solar cells, ZnO/ TiO2 films were synthesized by sol-gel process and deposited on ITO deposited glass substrates using the spin-coating technique. P3HT/PCBM blend layers were deposited by using electrospray deposition (ESD). To observe the thermal effects on the device efficiencies, the devices were annealed at different temperatures (up to 140 °C). The cell’s performance parameters were compared at an annealing temperature of 120 °C. Comparing the performance parameters of both types of OSCs at an annealing temperature of 120 °C, the power conversion efficiency (PCE) the 1.62% is found for direct-structured OSC while 1.57% and 1.0% for ZnO/ TiO2-based inverted structures, respectively. Interestingly, the enhanced device performance parameters were obtained with oxides-based OSCs. Compared to ZnO-based inverted OSC, the TiO2-based inverted OSC has lower efficiency which might be due to the highly resistive surface of TiO2 with deep-level traps. These traps can be reduced by light soaking to achieve the optimal power conversion efficiency.

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In-depth investigation of the charge extraction efficiency for thermally annealed inverted bulk-heterojunction solar cells

Abstract: In-depth investigation of the charge extraction efficiency for thermally annealed inverted bulk-heterojunction solar cells

Cited by 3 publications

References 58 publications

Quantifying the Damage Induced by X-ray Photoelectron Spectroscopy Depth Profiling of Organic Conjugated Polymers

Quantifying the Damage Induced by X-ray Photoelectron Spectroscopy Depth Profiling of Organic Conjugated Polymers

On the Growth of Evaporated NaF on Phenyl-C61-butyric Acid Methyl Ester and Poly(3-hexylthiophene)

Fabrication of bulk heterojunction organic solar cells with different configurations using electrospray

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