Flexible, light trapping substrates for organic photovoltaics

Park, Yoonseok; Berger, Jana; Tang, Zheng; Müller‐Meskamp, Lars; Lasagni, Andrés Fabían; Vandewal, Koen; Leo, Karl

doi:10.1063/1.4962206

Cited by 32 publications

(33 citation statements)

References 31 publications

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“…An enhancement in PCE from 6.62% to 7.48% was reported for flexible OPVs having nanopatterned flexible polymer substrates fabricated by this method . Moreover, enhancements in optical characteristics and PCE were reported for OPVs having the thinnest film substrate ever reported (125 µm) with nanopatterns fabricated by the laser‐carving method …”

Section: Introductionmentioning

confidence: 74%

“…The nanopatterning of the polymer substrates of OPVs can be performed by two methods. The first is the laser‐carving method in which nanopatterns are carved by a laser beam onto the surface of the substrate . An enhancement in the PCE from 6.62% to 7.70% has been reported for flexible OPVs using nanopatterned flexible polymer substrates fabricated by this method .…”

Section: Introductionmentioning

confidence: 99%

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Nanograting Structured Ultrathin Substrate for Ultraflexible Organic Photovoltaics

et al. 2020

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The nanopatterning of the surfaces of polymer substrates enhances the performances of photovoltaics. Ultraflexible organic photovoltaics (OPVs) are one of the promising energy harvesters for wearable electronics. A reduction in incident light angle dependence while maintaining the power conversion efficiency (PCE) is desirable for wearable electronics devices in which the angle of incident light continuously changes due to the deformation of the device. However, the nanopatterning of the ultrathin polymer substrates of ultraflexible OPVs using the reported methods is challenging because they fatally damage the substrates. Here, the fabrication of ultraflexible OPVs having a low incident light angle dependence while maintaining a PCE of 10.5% by developing ultrathin nanograting polymer substrates is reported. The nanograting‐patterned fluorinated polymer enables the formation of periodic nanograting structures onto the back surface of a 1 µm thick polymer substrate having a pitch of 760 nm and a height of 100 nm, while the opposite surface remains flat after the formation of the planarization layer. Furthermore, with the nanopatterning of the ultrathin substrate, electron‐transporting layer, and active layer, the ultraflexible OPVs exhibit a PCE of 10.8%. The combination of new materials with the developed patterning method is expected to afford even greater performances.

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Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Nanograting Structured Ultrathin Substrate for Ultraflexible Organic Photovoltaics

et al. 2020

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“…Schematics of different heterojunction p–i–n concepts in organic photovoltaics: a) planar heterojunction, b) an ideal bulk heterojunction, and c) a real bulk heterojunction. Reproduced with permission . Copyright 2016, Technische Universität Dresden.…”

Section: Limitations Of Organic Solar Cellsmentioning

confidence: 99%

“…Similar as for inorganic solar cells, many different types of optical in‐coupling components have been studied for achieving high‐performance OSCs since 2000 . For instance, photonic crystals, surface patterning, surface plasmon polariton (SPP) resonances, and scattering layers . In the following sections, periodic structures, scattering, and multijunction devices will be discussed as means of achieving an increased light absorption in organic solar cells.…”

Section: Optical In‐couplingmentioning

confidence: 99%

“…As a result, constructing pattern structures that are higher than the OSC layer is challenging, and the period and size of the structures are restricted. Moreover, when OSCs are built on a planar surface and the patterned structures are exposed to the ambient environment, problems from external damage and dirt should be considered . In the following sections, work on addressing these difficulties is discussed.…”

Section: Optical In‐couplingmentioning

confidence: 99%

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Optical In‐Coupling in Organic Solar Cells

2018

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thus offering an environmentally friendly approach. Furthermore, the use of simple low-temperature processing techniques makes it a potentially low-cost technology. However, efficiency and stability are so far lacking, hampering the full exploitation of the potential this technology has in these new applications. After the demonstration of the first reasonably performing organic solar cell by Tang [1] achieving approximately 1% efficiency, much effort has been put into improving these values. Nowadays, efficiencies well beyond 10%, and even over 13% have been reached, [2,3] however, with hard-to-synthesize polymers that so far have not shown sufficient stability for practical applications.Closer to commercial exploitation, solar cells based on oligomers (also termed "small molecules") and the material class used by Tang et al. [1] are investigated and introduced in their pioneering papers. [4][5][6][7][8][9][10][11][12][13][14][15] This material class can be either deposited by vacuum evaporation or solution processing. [16][17][18][19][20][21] The advantage of vacuum evaporation is that very pure layers without solvent residuals are produced, which is favorable for a higher stability of the cells. Also, they allow several cells to be very easily integrated into stacked multijunction devices. [22] With multijunction cells, Heliatek has reached an efficiency of 13.2% using proprietary materials that allow long lifetimes and can be readily manufactured. [23] Single-junction devices with similar published materials achieve above 8% efficiency [24] and above 10% in single-junction and tandem devices, respectively. [25] While these values are much improved as compared to the pioneering work of Tang, there is still a large gap to be closed to reach efficiencies comparable to silicon solar cells and other inorganic PV technologies.Here, first we will address limitations of organic solar cells, such as short exciton diffusion length, voltage, and transport problems. After that, various approaches to solve these challenges will be introduced. These include the bulk heterojunction, multijunction devices, and periodically patterned structures on substrates or active layers. Among these approaches, we focus on optical in-coupling, which allows more photons to be funneled into the thin organic active layers, yielding higher efficiencies. Limitations of Organic Solar CellsAlthough organic solar cells have huge potential and acceptable power conversion efficiencies (PCEs), they still have limitations caused by a short exciton diffusion length, charge transport, and low open-circuit voltage (V oc ). In this section, we briefly summarize why OSCs lack in efficiency, and optical in-coupling is required to improve the performance.Organic photovoltaics have many unique properties, such as flexibility, transparency, and low weight, which allows novel applications to be addressed. A remaining challenge is to increase the power conversion efficiencies into the range that is offered by conventional inorganic photovoltaics. Due to the li...

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Advanced Photonic Processes for Photovoltaic and Energy Storage Systems

et al. 2017

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Solar-energy harvesting through photovoltaic (PV) conversion is the most promising technology for long-term renewable energy production. At the same time, significant progress has been made in the development of energy-storage (ES) systems, which are essential components within the cycle of energy generation, transmission, and usage. Toward commercial applications, the enhancement of the performance and competitiveness of PV and ES systems requires the adoption of precise, but simple and low-cost manufacturing solutions, compatible with large-scale and high-throughput production lines. Photonic processes enable cost-efficient, noncontact, highly precise, and selective engineering of materials via photothermal, photochemical, or photophysical routes. Laser-based processes, in particular, provide access to a plethora of processing parameters that can be tuned with a remarkably high degree of precision to enable innovative processing routes that cannot be attained by conventional approaches. The focus here is on the application of advanced light-driven approaches for the fabrication, as well as the synthesis, of materials and components relevant to PV and ES systems. Besides presenting recent advances on recent achievements, the existing limitations are outlined and future possibilities and emerging prospects discussed.

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Flexible, light trapping substrates for organic photovoltaics

Cited by 32 publications

References 31 publications

Nanograting Structured Ultrathin Substrate for Ultraflexible Organic Photovoltaics

Nanograting Structured Ultrathin Substrate for Ultraflexible Organic Photovoltaics

Optical In‐Coupling in Organic Solar Cells

Advanced Photonic Processes for Photovoltaic and Energy Storage Systems

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