Efficient Semitransparent Organic Solar Cells with Tunable Color enabled by an Ultralow‐Bandgap Nonfullerene Acceptor

Cui, Yong; Yang, Chenyi; Yao, Huifeng; Zhu, Jie; Wang, Yuming; Jia, Guoxiao; Gao, Feng; Hou, Jianhui

doi:10.1002/adma.201703080

Cited by 340 publications

(287 citation statements)

References 48 publications

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“…Consequently limited tunability of energy levels of frontier molecular orbitals (FMOs), tedious purification, and morphological instability. [14] For the electron-rich central core, a variety of π-conjugated fused rings with distinct side chains, such as alkyl, alkylphenyl, and alkylthienyl, have been developed to meet the demands of sufficient solubility, optical, electrochemical, and morphological properties. [11] Encouragingly, the PCEs of nonfullerene solar cells (NFSCs) based on FREAs have been improved substantially from 6% to ≈14% for single-layer cells in the last few years.…”

Section: Introductionmentioning

confidence: 99%

Facile Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)–Based Acceptors with Fine‐Tuned Optoelectronic Properties: Toward Efficient Additive‐Free Nonfullerene Organic Solar Cells

Wang

Liu

Koh

et al. 2019

Advanced Energy Materials

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A series of polycyclic aromatic hydrocarbons (PAHs) with extended π‐conjugated cores (from naphthalene, anthracene, pyrene, to perylene) are incorporated into nonfullerene acceptors for the first time. Four different fused‐ring electron acceptors (FREAs), i.e., DTN‐IC‐2Ph, DTA‐IC‐3Ph, DTP‐IC‐4Ph, and DTPy‐IC‐5Ph, are prepared via simple and facile synthetic procedures, yielding a remarkable platform to study the structure–property relationship for nonfullerene solar cells. With the PAH core being extended systematically, the gradually redshifted absorption with enhanced molar extinction coefficient (ε) is realized, the energy level of the highest occupied molecular orbital is up‐shifted, and the electron mobility is greatly enhanced. Meanwhile, the solubility decreases and the molecular packing becomes strengthened. As a result, with an optimized combination of these characteristics, DTP‐IC‐4Ph attains good solubility, high molar extinction coefficient, complementary absorption, suitable morphology, well‐matched energy levels, as well as efficient charge dissociation and transport in blend film. Consequently, the DTP‐IC‐4Ph‐based solar cells with a donor polymer, poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T) exhibit a promising power conversion efficiency of 10.37% without any additives, which is close to the best performance achieved in additive‐free nonfullerene solar cells (NFSCs). The results demonstrate that the PAH building blocks have great potential for the construction of novel FREAs for efficient additive‐free NFSCs.

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Section: Introductionmentioning

confidence: 99%

Facile Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)–Based Acceptors with Fine‐Tuned Optoelectronic Properties: Toward Efficient Additive‐Free Nonfullerene Organic Solar Cells

Wang

Liu

Koh

et al. 2019

Advanced Energy Materials

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“…[10,11] Finding ways to maximize V OC requires one to reduce the energy loss (E loss = E g opt -eV OC ) that occurs as a result of the multiple states that follow exciton generation. [13][14][15][16][17][18] Tunability of E g opt through molecular design allows one to tailor NIR absorption characteristics. [13][14][15][16][17][18] Tunability of E g opt through molecular design allows one to tailor NIR absorption characteristics.…”

mentioning

confidence: 99%

Bandgap Narrowing in Non‐Fullerene Acceptors: Single Atom Substitution Leads to High Optoelectronic Response Beyond 1000 nm

Lee

Seifrid

et al. 2018

Advanced Energy Materials

144

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absorption spectra extending to the NIR region have been designed and applied to the fabrication of OSCs. [6][7][8] A critical challenge arises as one decreases optical bandgaps (E g opt ) with respect to simultaneously achieving a high external quantum efficiency (EQE) and high open-circuit voltage (V OC ). [9] This challenge is due to the counterbalance between the driving force for charge separation, which aids in photocurrent generation, and voltage loss in the cell. [10,11] Finding ways to maximize V OC requires one to reduce the energy loss (E loss = E g opt -eV OC ) that occurs as a result of the multiple states that follow exciton generation. [12] Narrow bandgap (NBG) non-fullerene acceptors (NFAs) have emerged as the next generation of electron acceptors in OSCs. [13][14][15][16][17][18] Tunability of E g opt through molecular design allows one to tailor NIR absorption characteristics. [19,20] Considering that the maximum human photopic sensitivity is 555 nm and the maximum human scotopic sensitivity is 507 nm, [21] transparent photoactive materials should predominantly absorb solar radiation from ≈650 nm into the NIR region for semitransparent solar cell applications. In addition, since ≈50% of solar radiation intensity is in the NIR region, the development of NBG-NFAs with E g opt below ≈1.35 eV is desirable to effectively harvest solar NIR radiation. [1] Another encouraging feature of NFAs is that the energetic offsets that drive charge generation are small (<0.3 eV), [18,[22][23][24] which is beneficial for maintaining low E loss . Despite these desirable features, there has been less consideration for designing NBG-NFAs for transparent/NIR absorbing OSC applications. To address this challenge and expand the design of NIR harvesting acceptor molecules, we demonstrate in this contribution a new molecular design for ultra NBG-NFA materials with strong NIR response and small E loss .The two NBG NFAs described in this contribution are COTIC-4F and SiOTIC-4F (Figure 1a). Their molecular design includes incorporation of a cyclopentadithiophene (CPDT), or dithienosilole (DTS), unit as the central donor (D) fragment, which is flanked by two alkoxythienyl units (D′) to form an electron-rich D′-D-D′ central core. The D′-D-D′ units are end-capped with Two narrow bandgap non-fullerene acceptors (NBG-NFAs), namely, COTIC-4F and SiOTIC-4F, are designed and synthesized for the fabrication of efficient near-infrared organic solar cells (OSCs). The chemical structures of the NBG-NFAs contain a D′-D-D′ electron-rich internal core based on a cyclopentadithiophene (or dithienosilole) (D) and alkoxythienyl (D′) core, end-capped with the highly electron-deficient unit 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (A), ultimately providing a A-D′-D-D′-A molecularconfiguration that enhances the intramolecular charge transfer characteristics of the excited states. One can thereby reduce the optical bandgap (E g opt ) to as low as ≈1.10 eV, one of the smallest values for NFAs reported to date. In bulk-he...

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“…[1][2][3][4][5][6] While such efforts have resulted in a library of active materials, they have also presented challenges for commercial viability due to the different processes and costs associated with employing distinct active materials to display different colors. [1][2][3][4][5][6] While such efforts have resulted in a library of active materials, they have also presented challenges for commercial viability due to the different processes and costs associated with employing distinct active materials to display different colors.…”

mentioning

confidence: 99%

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

Kim

Son

Shafian

et al. 2018

Advanced Optical Materials

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protocols that tailor the absorption spectrum of the active material. [1][2][3][4][5][6] While such efforts have resulted in a library of active materials, they have also presented challenges for commercial viability due to the different processes and costs associated with employing distinct active materials to display different colors. Their use has also resulted in varied performances among devices of different colors, adding to the difficulty for practical implementation. Furthermore, challenges in organic synthesis have limited the achievable types of color and their spectral purity. In this work, we introduce a strategy that enables a single active material that absorbs uniformly across the visible range to display different colors with high spectral purity and consistent device performances through the implementation of a color filtering (CF) electrode. The electrode consists of a Ag-TiO x -Ag Fabry-Perot (FP) resonant cavity, where the thickness of the TiO x layer determines the spectral position of the transmission peak and the inner Ag layer functions as an electrical contact. The electrode also functions as a mirror for all wavelengths of light except that within the resonant band (i.e., the spectral transparency window) of the CF. Therefore, light that has not been selectively transmitted may reflect back into the active material, contributing to additional charge generation. This implies that the short-circuit current density, which is largely a function of the optical absorption, must be higher for a CF-integrated OPV compared to a transparent OPV, under the condition that the two devices show similar peak transmission efficiencies.The use of photonic structures as optical filters in OPVs or inorganic solar cells has been previously reported in the form of distributed Bragg reflectors, [7][8][9] photonic arrays, [10][11][12] and plasmonic resonators. [13][14][15] While such filters enable various colors to be transmitted or reflected through tuning of the characteristic dimension of the filter components, in many cases they suffer from increased fabrication costs and duration because of the structural complexity. Moreover, photonic structures employing low-loss dielectrics exhibit poor electrical conductivity, precluding their use as an electrode. Finally, the structural anisotropy intrinsic to 1D or 3D photonic structures can result in asymmetric responses for light incident from above and below the device. Such behavior can complicate design schemes for creating bidirectional colored windows.Colorful, semitransparent organic photovoltaic cells (OPVs) are increasing in demand due to their applicability in aesthetically fashioned powergenerating windows. The traditional method of generating different colors in OPVs has been through employing different active materials exhibiting distinct absorption spectra. This can complicate fabrication processes for production and cause deviations in device performance among differently colored OPVs. Herein, semitransparent and colorful OPVs with a single broadban...

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Efficient Semitransparent Organic Solar Cells with Tunable Color enabled by an Ultralow‐Bandgap Nonfullerene Acceptor

Cited by 340 publications

References 48 publications

Facile Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)–Based Acceptors with Fine‐Tuned Optoelectronic Properties: Toward Efficient Additive‐Free Nonfullerene Organic Solar Cells

Facile Synthesis of Polycyclic Aromatic Hydrocarbon (PAH)–Based Acceptors with Fine‐Tuned Optoelectronic Properties: Toward Efficient Additive‐Free Nonfullerene Organic Solar Cells

Bandgap Narrowing in Non‐Fullerene Acceptors: Single Atom Substitution Leads to High Optoelectronic Response Beyond 1000 nm

Semitransparent Blue, Green, and Red Organic Solar Cells Using Color Filtering Electrodes

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