Formation of Organic Alloys in Ternary-Blend Solar Cells with Two Acceptors Having Energy-Level Offsets Exceeding 0.4 eV

Khlyabich, Petr P.; Sezen-Edmonds, Melda; Howard, Jenna B.; Thompson, Barry C.; Loo, Yueh‐Lin

doi:10.1021/acsenergylett.7b00620

Cited by 27 publications

(25 citation statements)

References 55 publications

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“…It is possible to reduce E loss of PBDB-T:IEICO-4F:3TT-FIC-based ternary PSCs to obtain a large V OC value. [30,51] To evaluate the photovoltaic performance of our system and unravel the nature of its high V OC and small E loss value, photoluminescence (PL) quenching and time-resolved PL (TRPL) were employed to investigate the exciton dissociation and energy transfer at the donor/acceptor (D/A) interface. www.advopticalmat.de PBDB-T:IEICO-4F and IEICO-4F:3TT-FIC, and ternary films of PBDB-T:IEICO-4F:3TT-FIC).…”

Section: Resultsmentioning

confidence: 99%

“…[25,26] Zhang's group reported a record PCE value of over 16% by using ternary films as the photoactive layer. [27] Notably, several excellent groups, such as Brabec's group, [28] Yang's group, [29] Thompson's group, [30] Cao's group, [31] Zhan's group, [32] and Hou's group, [33] have summarized the progress in ternary PSCs. According to the previous reports, three high photovoltaic parameters can hardly be simultaneously achieved in one binary PSC, which is limited by the intrinsic properties of the used materials.…”

Section: Introductionmentioning

confidence: 99%

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Small Energy Loss and Broad Energy Levels Offsets Lead to Efficient Ternary Polymer Solar Cells from a Blend of Two Fullerene‐Free Small Molecules as Electron Acceptors

Wang

2019

Advanced Optical Materials

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the new polymer PE2 and PE63 as donor and with Y6 as acceptor, and achieved the better photovoltaic performance. [6,7] PSCs have several advantages, such as their light absorption tunability, mechanical flexibility, roll-to-roll manufacturing capability and so on. However, the PCE of PSCs is still inferior to their inorganic counterparts. One of the most significant factors that hinders their photovoltaic performance is the relatively large energy loss (E loss ) in the open-circuit condition with respect to the energy level offsets between the donor and acceptor, which leads to the low open-circuit voltage (V OC ) value. [8,9] In addition, there are several disadvantages involving exciton dissociation and charge carrier recombination within the photoactive layer which might function to enhance the photovoltaic performance. In parallel, the narrow spectral absorption of fullerene acceptors (e.g., [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM)) falling in the short-wavelengths region (from 300 to 450 nm) inherently limits the photonic absorption since most of the photon flux occurs in the visible range of the solar spectrum (longer than 450 nm). At the same time, the fullerene derivatives have the disadvantage of having a deep lowest unoccupied molecular orbital (LUMO) energy level, which limits the energy level offset between the donor and acceptor and leads to small open-circuit voltages (V OC ). [10,11] Fullerene-free electron acceptors that enable adjustable energy levels and broad visible light absorption spectra have been developed and synthesized. For instance, the absorption peak of the fullerene-free acceptor 2,2′-((2Z,2′Z)- (((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-sindaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl)) bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IEICO-4F) is located in the near-infrared region (the absorption peak is at 835 nm), and it has a shallow LUMO energy level (the LUMO energy level is at −4.13 eV) relative to those of PC 71 BM. [12] The new fullerenefree molecule, thieno[3,2-b]thiophene-2-(5,6-difluoro-3-oxo-2-2,3-dihydro-1H-ioden-1-ylidene)malononitrile (3TT-FIC) has a longer wavelength absorption window (the absorption peak is located at 810 nm) and a shallower LUMO energy level (the LUMO energy level is at −4.02 eV). [13] Recently, ternary strategies that use either a blend of one donor and two acceptor materials or two donor and one Ternary polymer solar cells (PSCs) are fabricated that consisted of a blend of IEICO-4F and 3TT-FIC as electron acceptors and PBDB-T as an electron donor. The power conversion efficiency (PCE) of ternary PSCs is increased from 9.9% to 11.22% via the blend of IEICO-4F and 3TT-FIC as electron acceptors (the ratio of IEICO-4F:3TT-FIC is 6:4), which enhances the opencircuit voltage (V OC ) from 0.71 to 0.78 V. The main contribution of the blended acceptor is its broad energy level offset between ...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Small Energy Loss and Broad Energy Levels Offsets Lead to Efficient Ternary Polymer Solar Cells from a Blend of Two Fullerene‐Free Small Molecules as Electron Acceptors

Wang

2019

Advanced Optical Materials

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“…The highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) level of the third component are vital parameters to form efficient charge transport channels in ternary active layers with two donors or acceptors, respectively. Meanwhile, the appropriate energy levels of the third component can achieve relatively high open circuit voltage (V OC ) compared with the host binary PSCs, leading to the minimal energy loss by employing ternary strategy [15,[25][26][27][28][29][30][31]. Most of efficient ternary PSCs work under alloy-like model, which were well designed by employing two donors or two acceptors with good compatibility, appropriate energy levels and complementary absorption spectra [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Alloy-like ternary polymer solar cells with over 17.2% efficiency

et al. 2020

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“…For instance, Thompson and coworkers reported that the utilization of the PC 61 BM:P3HT75‐ co ‐EHT25:P3HTT‐DPP system is a practical strategy to improve the V oc and efficiency of ternary OSCs . A previous report suggested that the V oc of ternary OSCs was defined by the offset between the higher of the two HOMO energy levels of the donors and the LUMO energy level of the acceptor in two‐donors/one‐acceptor ternary blends . Alloy‐based ternary blends, comprising of a fullerene‐derivative acceptor and a nonfullerene acceptor, have been demonstrated for increasing the V oc of ternary OSCs.…”

Section: Introductionmentioning

confidence: 99%

A Machine Learning–Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells

Lee

2019

Advanced Intelligent Systems

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Organic solar cells (OSCs) based on ternary blends are among the most promising photovoltaic technologies. To further improve the power conversion efficiency (PCE), the materials selection criteria must be focused on achieving high open-circuit voltage (V oc ) through the alignment of the energy levels of the ternary blends. Hence, machine-learning approaches are in high demand for extracting the complex correlation between V oc and the energy levels of the ternary blends, which are crucial to facilitate device design. Herein, the datadriven strategies are used to generate a model based on the available experimental data, and the V oc is then predicted using available machine-learning methods (the Random Forest regression and the Support Vector regression). In addition, the Random Forest regression is developed to find the appropriate energy-level alignment of ternary OSCs and to reveal the relationship between V oc and electronic features. Finally, an analysis based on the ranking of variables in terms of importance by the Random Forest model is performed to identify the key feature governing the V oc and the performance of ternary OSCs. From the perspective of device design, the machine-learning approach provides sufficient insights to improve the V oc and advances the comprehensive understanding of ternary OSCs.

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Formation of Organic Alloys in Ternary-Blend Solar Cells with Two Acceptors Having Energy-Level Offsets Exceeding 0.4 eV

Cited by 27 publications

References 55 publications

Small Energy Loss and Broad Energy Levels Offsets Lead to Efficient Ternary Polymer Solar Cells from a Blend of Two Fullerene‐Free Small Molecules as Electron Acceptors

Small Energy Loss and Broad Energy Levels Offsets Lead to Efficient Ternary Polymer Solar Cells from a Blend of Two Fullerene‐Free Small Molecules as Electron Acceptors

Alloy-like ternary polymer solar cells with over 17.2% efficiency

A Machine Learning–Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells

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