Ab Initio Study of Two-Dimensional Cross-Shaped Non-Fullerene Acceptors for Efficient Organic Solar Cells (original) (raw)
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DFT and TDDFT Studies of Non-Fullerene Organometallic Based Acceptors for Organic Photovoltaics
Recently, non-fullerenes acceptor based solar cells have replaced the fullerenes based ones due to their higher enhanced photochemical and thermal stability. Hence, in this work, six molecules based on D-A and D-AD topologies have been designed, where dipyridophenazine as acceptor (which is attached with a metal atom) is attached with triphenylamine as the donor fragment. In case of D-A topology based A1-A3 molecules, donor: acceptor ratio is 1:1 while in D-AD type B1-B3 molecules it is 1:2. Computational analyses based on density functional and time-dependent density functional are carried out to investigate the effect of Ca, Mg, and Be metals in both topologies. Reduced orbital energy levels in all designed molecules refer to them as good acceptors in both topologies. Ca-complexed (A1 and B1) acceptors in both topologies after the optimal function have shown a smaller energy gap of 0.6 eV than those of reference R and all other designed molecules. In case of D-AD topology, B1 showed a significant red-shift of 72 nm than that of R. While D-A topology-based A1 showed a more or less similar absorption wavelength like R. Besides, absorption peaks of Mg and Be-complexed molecules are stronger in the case of D-AD topology. In a nutshell, this computational investigation approved these molecules as efficient and effective for non-fullerene organometallic based acceptors for organic solar cell devices.
Optical and Quantum Electronics
Non fullerene small acceptor molecules in organic photovoltaics are proven beneficial than the traditional fullerene based acceptors for their fine contribution in organic solar cells. Researchers are constantly doing efforts for designing novel acceptor materials with promising photovoltaic properties. Designing of novel molecules by end-capped modifications is a convenient strategy to obtain high efficiency acceptor molecules for OSCs. Herein, we studied optoelectronic characteristics of five novel acceptor-donor-core-donor-acceptor configured small acceptor molecules (S1-S5) after end-capped modifications of recently synthesized DF-PCIC molecule. Designed molecules S1-S5 consist of 1,4-difluorobenzene (as central core), 4,4-bis(2-ethylhexyl)-2,6-dimethyl-4H-cyclopenta[1,2-b:5,4-b′]dithiophene as donor which directly attached with different end-capped acceptors. The electronic and optical properties of newly designed (S1-S5) molecules are examined and compared with reference molecule with the aid of DFT and TD-DFT. Certain key parameters like frontier molecular orbitals analysis, density of states, dipole moment, binding energy along Electronic supplementary material The online version of this article (
Research Article, 2019
We design four high performance non-fullerene acceptor materials by applying strong electron withdrawing groups at the end of AD A -D-A type organic solar cells molecules and compute their different opto-electronic and photovoltaic properties, including absorption spectrum, electron density, solubility strength, charge mobilities for electrons and holes, stability of HOMO/LUMO energy orbitals, excitation energies required for charge transfer mechanisms, and morphology of device with the help of DFT approaches using the principles of quantum mechanics. The newly designed molecules showed strong absorption bands between 420 to 650 nm, low HOMO energy values from −7.24 to −7.28 eV, large % ETC from 35 to 65%, and small excitation energies from 2.28 to 2.47 eV in the organic solvent chloroform; 410 to 620 nm, 31 to 64%, and 2.42 to 2.56 eV, respectively, in gas phase conditions. Solubility strengths of the newly designed molecules were also high, varying from 5.3039 to 18.4749 Debye in the ground and excited states. Power conversion efficiencies of the designed molecules are expected to be high because they show better results than the R molecule. Open circuit voltages of designed molecules range from 3.67 to 3.54 V with respect to the PCBM. Reorganization energies for electron transport vary from 0.0153 to 0.0175 eV and for hole transport from 0.0231 to 0.0254 eV. This computational study proves that the newly designed molecules with non-fullerene acceptors are superior and thus are recommended for the future construction of high performance organic solar cells devices.
Designation and Match of Non-Fullerene Acceptors with X-Shaped Donors toward Organic Solar Cells
In this work, a series of PDI derivatives by substituting different aromatic groups at bay position of PDI molecule (dipyrollo pyrrole as PDI-I, dithieno pyrrole as PDI-II, furopyrazine as PDI-III, naptho thiadiazole as PDI-IV and thiadiazolo pyridine as PDI-V) were investigated for photovoltaic applications. Optoelectronic properties of investigated molecules were studied using DFT methods at B3LYP/6-31G (d, p) level of theory. Among investigated molecules, PDI-I showed the smallest Eg than those of reference (R) and PDI molecules. The absorption spectra of PDI-I displayed bathochromic shift of 107 nm as compared to R. All investigated molecules PDI-I, PDI-II, PDI-III, PDI-IV and PDI-V also resulted a significant bathochromic shift of 308, 151, 148, 75 and 61 nm, respectively than that of PDI molecule. The reorganization energy analysis indicated that PDI-I and PDI-II could act as excellent hole transporting materials while PDI-III and PDI-IV as excellent electron transporting materials. However, PDI-V acted as ambipolar due to comparable λ e and λ h values. All investigated PDI-I to PDI-V molecules could act as suitable acceptors with previously designed X1 and X2 donors and their V oc ranged from 0.97-1.51 V with X1 and from 0.80-1.34 V with X2. In a nutshell, this computational analysis proved that investigated molecules have potential to be used in cost effective and efficient nonfullerene organic solar cell devices.
DFT Based Modeling of Asymmetric Non-Fullerene Acceptors for High-Performance Organic Solar Cell
2022
AbstractFive new asymmetric NFA-based polymer solar cells i.e., N1-N5 are designed by doing modification in terminal groups of the acceptor part of experimentally synthesized reference molecule with (4,4,9,9-tetramethyl-4,9 dihydroselenopheno [2’,3’:5,6]-s-indaceno [1,2-b] thiophene) core. Frontier molecular orbital analysis is used to study their photovoltaic and optoelectronic properties. It confirmed the electrons' transportation from the donor to the acceptor part. It stated that all molecules have a lower bandgap than R and N2 has the lowest bandgap of 2.01 eV. The molecular orbital potential analysis confirmed the electron-withdrawing properties of the terminal groups. Optical properties studies evaluated maximum absorption with transition energies. All newly designed molecules N1-N5 show higher λmax values than R i.e., in the range of 680-740 nm with N2 having the highest λmax of 735 nm and lowest transition energy of 1.69 eV. Dipole moment studies showed that N3 has a ma...
Journal of Molecular Modeling, 2020
Non-fullerene small molecular acceptors (NFSMAs) exhibit promising photovoltaic performance which promoted the rapid progress of organic solar cells (OSCs). In this study, an attempt is done to explore indenothiophene-based high-performance small molecular electron acceptors for organic solar cells. We have designed five acceptor molecules (M1-M5) with strong donor moiety indenothiophene linked to five different end-capped group acceptor moieties: diflouro-2-methylene-3-oxo-2,3dihydroindene-1-ylidene)malononitrile (A1), 1-(dicyanomethylene)-2-methylene-3-oxo-2,3-dihydro-1H-indene-5,6dicarbonitrile (A2), methyl-6-cyano-3-(dicyanomethylene)-2-methylene-1-oxo-2,3-dihydro-1H-indene-5-carboylate (A3), 2-(6-cyano-5-fluoro-2-methylene-3-oxo-2,3 dihydro-1H-indene-1-ylidene)malononitrile (A4), and (Z)-methyl 3-(benzo [c][1,2,5]thiadiazol-4-yl)-2-cyanoacrylate (A5) respectively. The structure-property relationship was studied and effects of structural modification on the optoelectronic properties of these acceptors (M1-M5) were determined systematically by comparing it with reference molecule R, which is recently reported as excellent non-fullerene-based small acceptor molecule. Among all designed molecules, M5 is proven as a suitable candidate for organic solar cell applications due to better photovoltaic properties including narrow HOMO-LUMO energy gap (2.11 eV), smallest electron mobility (λ e = 0.0038 eV), highest λ max values (702.82 nm in gas) and (663.09 nm in chloroform solvent) and highest open-circuit voltage (V oc = 1.49 V) with respect to Highlights • The detailed DFT and TDDFT calculations have been performed on novel indenothiophene-based high-performance NFSMAs. • Five acceptor molecules (M1-M5) with strong donor moiety indenothiophene linked to five different end-capped group acceptor moieties based on newly synthesized AIDIC molecule were designed and studied. • The electronic, optical, and photovoltaic properties were studied. • The studied compounds are proposed to be better entrants for OSC applications. • This work may provide useful means in designing of new photovoltaic compounds.
Spectroscopy of Charge-Transfer States in Non-fullerene Acceptor Organic Solar Cells
2019
Spectroscopy of Charge-Transfer States in Non-fullerene Acceptor Organic Solar Cells Wejdan Alsufyani The performance of non-fullerene acceptor (NFA)based organic solar cells (OSC) has shown continuous increase in recent years, reaching power‐conversion efficiencies up to 17% through the design and synthesis of efficient acceptor materials. Recent research is directed towards achieving higher efficiency of OSC, which is limited by the open-circuit voltage (Voc) which is lower than the Voc values achieved in inorganic or perovskites solar cells with comparable bandgaps. In this work, voltage losses in NFA based OSC were calculated by investigating charge‐transfer state energy (ECT) using electroluminescence spectroscopy and sensitive external quantum efficiency in three polymer:nonfullerene bulk heterojunction solar cells. PCE10:ITIC device acquired the highest ECT with a Voc of 0.82V, and a a power conversion efficiency (PCE) of 7.91%. While PCE10:O-IDTBR obtained the highest Voc of...
Energy Level Tuning of Non-Fullerene Acceptors in Organic Solar Cells
Journal of the American Chemical Society, 2015
The use of non-fullerene acceptors in organic photovoltaic devices could lead to enhanced efficiencies due to increased open-circuit voltages (VOC) and improved absorption of solar light. Here we systematically investigate planar heterojunction devices comprising peripherally substituted subphthalocyanines as acceptor, and correlate device performance with heterojunction energetics. Due to a balance between VOC and photocurrent, tuning of the interface energy gap is necessary to optimize power conversion efficiency in these devices. In addition, we explore the role of the charge transport layers in the device architecture. It is found that non-fullerene acceptors require adjusted buffer layers with aligned electron transport levels to enable efficient charge extraction, while the insertion of an exciton blocking layer at the anode interface further boosts photocurrent generation. These adjustments result in a planar heterojunction OPV device with 6.9% efficiency and a VOC above 1 V.