Ternary Organic Solar Cells with Minimum Voltage Losses

Wang, Chuanfei; Zhang, Wei; Meng, Xiangyi; Bergqvist, Jonas; Liu, Xianjie; Genene, Zewdneh; Xu, Xiaofeng; Yartsev, Arkady; Inganäs, Olle; Ma, Wei; Wang, Ergang; Fahlman, Mats

doi:10.1002/aenm.201700390

Cited by 58 publications

(65 citation statements)

References 57 publications

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“…The figure is adapted from reference. [15] The quantity Pout has its best value at the maximum power point (Pmax) as shown in the Figure6.2.…”

Section: Figure62 Typical Current-voltage (J-v) Curve and Power-voltmentioning

confidence: 98%

“…However, as the frontier edge of the respective ICT distribution likely will overlap, some integer charge transfer still can be expected (Figure 3.4b). [9,15,34,43] carries at the D/A interface is enhanced by the interface potential energy gradient generated by occupied ICT states. [43,44] Hence, there is a trade-off in terms of occupied integer charge transfer …”

Section: Integer Charge Transfer At the Interface Of Donor And Acceptmentioning

confidence: 99%

“…[2,34,41,42] In organic solar cell, when the EICT-of the acceptor is larger than the EICT+ of the donor, there should be charge transfer between donor and acceptor in the dark ground state and formation of the dipole at the interface, creating a vacuum level misalignment. In that case, the effective electrical gap can be reformulated [15] When the measured Voc is compared to optical gap, the Voc,loss can be expressed by the formula…”

Section: Voltage Losses In Organic Solar Cellmentioning

confidence: 99%

“…[12] Compared with the gas spectra, in solid film, the spectra of frontier orbital was broaden and the onset shift to low binding energy (high kinetic energy) due to relaxation. [9,12,14,15] Every molecule/polymer in the film has its own individual IP and EA, and the frontier part of the IP and EA distribution is often modeled as being Gaussian. The IP and EA of the film are …”

mentioning

confidence: 99%

“…Adapted from the reference. [15] Dexter energy transfer needs an overlap of the wavefunctions between energy donor and energy acceptor so as to allow electron exchange. Hence it just can take place over short distances, typically around 1.0 nm.…”

mentioning

confidence: 99%

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Electronic Structure of π-Conjugated Materials and Their Effect on Organic Photovoltaics

Wang¹

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The great tunability of structure and electronic properties of -conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability.Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided.Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here.

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“…The figure is adapted from reference. [15] The quantity Pout has its best value at the maximum power point (Pmax) as shown in the Figure6.2.…”

Section: Figure62 Typical Current-voltage (J-v) Curve and Power-voltmentioning

confidence: 98%

Section: Integer Charge Transfer At the Interface Of Donor And Acceptmentioning

confidence: 99%

Section: Voltage Losses In Organic Solar Cellmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Electronic Structure of π-Conjugated Materials and Their Effect on Organic Photovoltaics

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A Terminally Tetrafluorinated Nonfullerene Acceptor for Well‐Performing Alloy Ternary Solar Cells

Chen

Liao

et al. 2019

Adv Funct Materials

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Fabricating ternary solar cells is a pivotal strategy to improve the power conversion efficiencies (PCEs) of organic photovoltaic devices. However, it is still a challenge to simultaneously improve the performance parameters of ternary devices. Therefore, the third ingredient in ternary blends should be precisely designed or selected. Herein, a new medium‐bandgap small‐molecule acceptor, namely, 3,9‐bis(2‐methylene‐(3‐(1‐(3,5‐dimethylphenyl)‐1cyanomethylene)indanone))‐5,5,11,11‐tetrakis‐(4‐hexylphenyl)dithieno[2,3‐d:2′,3′‐d′]‐sindaceno[1,2‐b:5,6‐b′]dithiophene (ITIF), is synthesized by end‐capping with a new fluorinated, asymmetric terminal group, (Z)‐2‐(3,5‐difluorophenyl)‐2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene) acetonitrile. Replacing the CN substituent with the asymmetric 3,5‐difluorophenyl substituent obviously up‐shifts the lowest unoccupied molecular orbital (LUMO) level of ITIF to −3.78 eV, enlarges the bandgap to 1.82 eV, and improves the absorption coefficient to ≈50% higher than that of 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)indanone))‐5,5,11,11‐tetrakis‐(4‐hexylphenyl)dithieno[2,3‐d:2′,3′‐d′]‐sindaceno[1,2‐b:5,6‐b′]dithiophene (ITIC). Due to the similar structures, ITIF and ITIC can combine as an alloyed acceptor, which makes it convenient to tune the morphology and optical and electrochemical properties of ternary blends. The enhanced absorption coefficient of ITIF and the rapid fluorescence resonance energy transfer from ITIF to ITIC remarkably improve the absorption of the ternary blend film, hence compensating for the external quantum efficiency (EQE) curves. When ITIF is introduced into ternary solar cells based on 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):ITIF:ITIC blends, the PCEs of the ternary devices are increased from 9.2% to 10.5%, and the short‐circuit currents, open‐circuit voltages, and fill factors are simultaneously improved.

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Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

Jang

Rasool

Kim

et al. 2020

Adv Funct Materials

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Herein, non-fullerene acceptor-based organic photodiodes are compared with fullerene acceptor-based organic photodiodes. The non-fullerene acceptor, ethylhexyl-rhodanine-benzothiadiazole-coupled indacenodithiophene (eh-IDTBR)-based organic photodiodes show a higher detectivity (1.61 × 10 13 cm Hz 1/2 W −1) and a faster response time (≈2.7 µs) than the fullerene acceptor, [6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM)-based organic photodiodes (3.25 × 10 12 cm Hz 1/2 W −1 and ≈6.24 µs, respectively) owing to the excellent dark current suppression of the carrier injection and the low trap density of eh-IDTBR. Moreover, the eh-IDTBR-based photodetector shows better operational device stability than the fullerene counterpart under electrical and thermal stress. This is corroborated by the morphology and crystallography analyses, both of which reveal that the eh-IDTBR-containing photo-sensitive films remain intact after imposing an external stress. This study elucidates important key advantages of the non-fullerene acceptor, eh-IDTBR, and sets a milestone as it compares the non-fullerene acceptors and fullerene acceptors in organic photodiodes for the first time. This work sets a new record for the performance and stability of solution-processable non-fullerene acceptor-based organic photodiodes.

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Ternary Organic Solar Cells with Minimum Voltage Losses

Cited by 58 publications

References 57 publications

Electronic Structure of π-Conjugated Materials and Their Effect on Organic Photovoltaics

Electronic Structure of π-Conjugated Materials and Their Effect on Organic Photovoltaics

A Terminally Tetrafluorinated Nonfullerene Acceptor for Well‐Performing Alloy Ternary Solar Cells

Superior Noise Suppression, Response Time, and Device Stability of Non‐Fullerene System over Fullerene Counterpart in Organic Photodiode

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