Application In Organic Solar Cells Research Articles

Exploring the effect of end-capped modifications of carbazole-based fullerene-free acceptor molecules for high-performance indoor organic solar cell applications

Exploring the effect of end-capped modifications of carbazole-based fullerene-free acceptor molecules for high-performance indoor organic solar cell applications

A structurally simple linear conjugated polymer toward practical application of organic solar cells

PTTzF, a linear conjugated polymer donor featuring simple synthesis, high device efficiency, outstanding batch reproducibility, and good universality with different acceptors is a promising candidate for practical application of organic solar cells.

Designing dibenzosilole core based, A2-π-A1-π-D-π-A1-π-A2 type donor molecules for promising photovoltaic parameters in organic photovoltaic cells.

In this research work, four new molecules from the π-A-π-D-π-A-π type reference molecule "DBS-2PP", were designed for their potential application in organic solar cells by adding peripheral A2 acceptors to the reference. Under density functional theory, a comprehensive theoretical investigation was conducted to examine the structural geometries, along with the optical and photovoltaic parameters; comprising frontier molecular orbitals, density of states, light-harvesting effectiveness, excitation, binding, and reorganizational energies, molar absorption coefficient, dipole moment, as well as transition density matrix of all the molecules under study. In addition, some photo-voltaic characteristics (open circuit photo-voltage and fill factor) were also studied for these molecules. Although all the developed compounds (D1-D4) surpassed the reference molecule in the attributes mentioned above, D4 proved to be the best. D4 possessed the narrowest band-gap, as well as the highest absorption maxima and dipole moment of all the molecules in both the evaluated phases. Moreover, with PC61BM as the acceptor, D4 showed the maximum V OC and FF values. Furthermore, while D3 had the greatest hole mobility owing to its lowest value of hole reorganization energy, D4 exhibited the maximum electron mobility due to its lowermost value of electron reorganization energy. Overall, all the chromophores proposed in this study showed outstanding structural, optical, and photovoltaic features. Considering this, organic solar cell fabrication can be improved by using these newly derived donors at the donor-acceptor interfaces.

Magneto-electrical properties of nickel phthalocyanine thin film and its application in organic solar cells

The nickel phthalocyanine (NiPc) thin film has been explored for magneto-conductance and optoelectrical properties. The surface morphology and the opto-electrical properties of thin films of NiPc have been observed as a good candidate for the applications in polymer solar cells. The AFM images show an almost continuous surface over the studied area. The spin interaction, the disordering of the spins part, and their suitable models have been discussed by the magneto-conductance properties of the thin films. The relaxation time of carriers and traps filling phenomena with applied bias are discussed by the impedance spectroscopy. The thin films of NiPc have been introduced as a hole interface buffer layer in the standard structure of P3HT: PCBM solar cells. The power conversion efficiency (PCE) of the optimized solar cell with NiPc is ∼3.17% and the fill factor (FF) is ∼69%., these device parameters are higher (PCE increased by ∼65% and FF by ∼39%) as compared to the organic solar cells fabricated without NiPc thin films in the same batch. The improved performance of organic solar cells attributed due to lowering the series and shunt resistance.

Photovoltaic properties of hole transport materials for organic solar cell (OSC) applications: physiochemical insight and in silico designing

Hole transport materials (HTMs) play a dominant role in enhancing the photovoltaic and optoelectronic properties of solar cells. These materials efficiently transport the hole, which significantly boosts the power conversion efficiencies of solar cells. In order to obtain better photovoltaic materials with efficient optoelectronic characteristics, we theoretically designed five new hole transport materials (Y3D1–Y3D5) after end-capped donor modifications of the recently synthesized highly efficient hole transport material Y3N (R). The relationships among photovoltaic, photophysical, optoelectronic and structural properties of these newly designed molecular models were studied at 6-31G(d,p) basis set and MPW1PW91 functional levels. Time‐Dependent Density Functional Theory (TDDFT) and density functional theory (DFT) proved to be excellent approaches for the studied systems. Geometrical parameters, molecular orbitals (MOs), open-circuit voltage (Voc), energy of binding and density of states were calculated. Low reorganization energy (RE) was noted; compared with the parent molecule (Reference/R), the designed molecular models possess high mobility. Molecular electrostatic potential (MEP) also supports our conclusion. Last but not least, the Y3D3:PC61BM complex was also studied to comprehend the role of charge distribution. These analyses showed that our modelled molecules are more efficient than the Y3N molecule. Thus, recommendations are made for experimentalists to develop extremely efficient solar cells in the near future.

Investigations of the optical and electrical properties of carbon quantum dots doped conducting polymers for organic solar cell applications

Polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) have much more attention in energy applications owing to their optical and electrical properties. To overcome the problems associated with these polymers, the Up-Conversion Carbon Quantum Dot (UC-CQD) based materials are employed. That has more desirable features, like hydrophilicity, low toxicity, and high water solubility. The UC-CQD in the electrochemical field is creating great attention to photoluminescent behaviors and low specific capacitance. When UC-CQD is combined with the conducting polymers, the optical properties are enhanced with the help of energy transfer processes. By the advantage of electropolymerization technique, the solubility problems are tackled, because the monomer has coated on the substrate. Herein, the preparation and characterization of the UC-CQD doped, PPy, and PTh films have been reported and their optical and electrical properties are investigated. The band gap of PPy and PPy-CQD is analysed from Tauc plot and calculated to be 2.54 and 1.69 eV respectively. The 50% and 60% mass loss were observed in thermogravimetric analysis for PPy and PPy-CQD respectively. These materials can be used for organic solar cell applications in near future.

Structure–property relationship on insertion of fluorine- versus nitrogen substituents in wide bandgap polymer donors for non-fullerene solar cells: an interesting case study

This work provides structure–property relationship into the effect of the insertion of fluorine- and nitrogen substituents on the polymer backbone, which were tested for organic solar cells applications.

Organoboron molecules and polymers for organic solar cell applications.

Organic solar cells (OSCs) are emerging as a new photovoltaic technology with the great advantages of low cost, light-weight, flexibility and semi-transparency. They are promising for portable energy-conversion products and building-integrated photovoltaics. Organoboron chemistry offers an important toolbox to design novel organic/polymer optoelectronic materials and to tune their optoelectronic properties for OSC applications. At present, organoboron small molecules and polymers have become an important class of organic photovoltaic materials. Power conversion efficiencies (PCEs) of 16% and 14% have been realized with organoboron polymer electron donors and electron acceptors, respectively. In this review, we summarize the research progress in various kinds of organoboron photovoltaic materials for OSC applications, including organoboron small molecular electron donors, organoboron small molecular electron acceptors, organoboron polymer electron donors and organoboron polymer electron acceptors. This review also discusses how to tune their opto-electronic properties and active layer morphology for enhancing OSC device performance. We also offer our insight into the opportunities and challenges in improving the OSC device performance of organoboron photovoltaic materials.

A novel A–DA′D–A bifunctional small molecule for organic solar cell applications with impressive photovoltaic performance

A bifunctional small molecule BPM1 was synthesized. When BPM1 functions as an acceptor and a donor, the corresponding devices achieve the best PCEs of 7.1% and 14.8%, respectively, which are the highest values for OSCs based on bifunctional materials to date.

Theoretical Investigation by Dft and Tddft the Extension Ofπ-Conjugation of Novel Carbazole-Based Donor Materials for Bulk Heterojunction Organic Solar Cell Applications

Theoretical Investigation by Dft and Tddft the Extension Ofπ-Conjugation of Novel Carbazole-Based Donor Materials for Bulk Heterojunction Organic Solar Cell Applications

Progress in perylene diimides for organic solar cell applications.

Compared to fullerene materials, non-fullerene acceptor materials have in recent years been more widely used in organic solar cell devices due to their optical properties and due to the ease of carrying out syntheses to tune their electronic energy levels. Non-fullerene acceptors constitute a major focus of research in the development of bulk-heterojunction organic solar cells. Recent developments have yielded increased power conversion efficiency (PCE) levels for non-fullerene acceptor materials, with the PCE levels now shown to exceed 20%. Perylene diimide (PDI), a non-fullerene acceptor material, has been widely studied because of its good transmission capacity and strong electron affinity. This paper summarizes the application of PDI molecules as acceptor materials in organic solar cells in recent years, detailing the strategies and approaches of molecular design and their application effects.

Novel quad-rotor-shaped photovoltaic materials: first example of fused-ring non-fullerene acceptors with proficient photovoltaic properties for high-performance solar cells.

Development of novel materials for organic solar cells is a booming area of current research. Fused-ring electron accepters are the potential agents of revolution in organic photovoltaic devices and revealing high efficiency in organic solar cells. This study highlights the novel quad-rotor-shaped molecules as first example of efficient fused-ring non-fullerene acceptor materials with proficient photovoltaic parameters for their utilization in high-performance organic solar cells. First time, eight quad-rotor-shaped fused-ring electron accepters (QRFR-1-QRFR-8) are developed via modulating end-caps of experimentally synthesized (BFTT-TN) molecule (QRFR). Optoelectronic properties of proposed molecules are determined using frontier molecular orbitals (FMO), UV-Visible, density of state (DOS), overlap DOS (ODOS), transition density matrix (TDM) heat maps, open circuit voltage (Voc), binding energies (Eb), reorganization energy of electron (λe), hole (λh), charge transfer analysis, and compared with reference QRFR. All proposed fused-ring electron accepters disclose less energy gap and λmax in near IR region than QRFR after end-capped engineering. Highest Voc with respect to HOMOPM6-LUMOacceptor is found 1.66V in QRFR-6 than QRFR (1.63V). Eb values of QRFR-1-QRFR-8 are found better and comparable with QRFR. The λe is found smaller than QRFR in all molecules except QRFR-5. The proposed quad-rotor-shaped molecules exhibit proficient photovoltaic features and can serve as best candidate for organic solar cells when blended with PM6 film. This study not only enlightens the researchers to use end-capped reforms as effective tactic for designing materials, but also provides novel quad-rotor-shaped materials to experimentalist for synthesis and their usage in future application of organic solar cells.

In silico modelling of acceptor materials by End-capped and π-linker modifications for High-Performance organic solar Cells: Estimated PCE > 18%

Efficient acceptor materials are of great importance in improving the performance of organic solar cells. Electron transport materials play a crucial role in improving the power conversion efficiency (PCE) of photovoltaic devices. In recent years, great efforts have been made to develop new acceptor materials that can be used in organic solar cells (OSCs). Previous reports have shown the high efficiency of CH1007 as an acceptor material in OSCs application. In this study, we used CH1007 as a reference molecule (R) and developed four new acceptor materials (CF1-CF4) derived from CH1007 based on the tuning of the end-capped and π-linker units within the conjugated framework. Density functional theory calculations (DFT) were performed to determine the structural, optoelectronic, and charge transfer properties of the developed materials. CF1-CF4 exhibited narrow band gaps with a redshift of the absorption maxima compared to R, which will lead to an improvement in the PCE of OSC. Low reorganization energies of holes and electrons were determined for the designed molecules compared to the reference molecule, indicating high charge carrier transport within these molecules. Transition density matrix (TDM) analysis revealed the movement of electron density from the core block to the acceptor moieties via π-linkages. The photovoltaic parameters were investigated and we found a relevant open-circuit voltage (Voc) for the designed molecules. A mixing study was performed for PTB7-Th: CF3, which gave interesting results. Based on the founding results and comparison with R, we found that the designed molecules are promising materials that can be used as acceptors for high-efficiency OSCs.

Two-Dimensional Nanomaterials for Boosting the Performance of Organic Solar Cells

The thin-film organic solar cells (OSCs) are currently one of the most promising photovoltaic technologies to effectively harvest the solar energy due to their attractive features of mechanical flexibility, light weight, low-cost manufacturing, and solution-processed large-scale fabrication, etc. However, the relative insufficient light absorption, short exciton diffusion distance, and low carrier mobility of the OSCs determine the power conversion efficiency (PCE) of the devices are relatively lower than their inorganic photovoltaic counterparts. To conquer the challenges, the two-dimensional (2D) nanomaterials, which have excellent photoelectric properties, tunable energy band structure, and solvent compatibility etc., exhibit the great potential to enhance the performance of the OSCs. In this review, we summarize the most recent successful applications of the 2D materials, including graphene, black phosphorus, transition metal dichalcogenides, and g-C3N4, etc., adapted in the charge transporting layer, the active layer, and the electrode of the OSCs, respectively, for boosting the PCE and stability of the devices. The strengths and weaknesses of the 2D materials in the application of OSCs are also reviewed in details. Additionally, the challenges, commercialization potentials, and prospects for the further development of 2D materials-based OSCs are outlined in the end.

Charge transfer processes via tandem modification of efficient non-fullerene acceptors for organic solar cells

High-efficiency non-fullerene acceptors (NFAs) have extensive applications in organic solar cells (OSCs) instead of fullerene-based acceptors. Herein, the dithienothiophen[3.2-b]-pyrrolo-benzothiadiazole (BDP), chlorinated BDP-2Cl, BDP-4Cl and designed BDPN-4Cl have been investigated. One performed the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to study their optimized structures, frontier molecular orbitals (FMOs) and other photoelectric parameters, which showed that designed BDPN-4Cl displayed narrower band gaps, smaller reorganization energy, larger electrophilic index and wider absorption spectrum than prototypical NFAs, and it had a greater ratio of charge separation rate/charge recombination rate (KCS/KCR) for heterojunction. It was also found that the designed BDPN-4Cl exhibited the largest electron transport ability, which was conducive to the interfacial process. Structure modification at the end positions of NFAs, such as the π-extension at the end-capping, showed a synergistic effect on performance. Furthermore, one also estimated the ideal performance (VOC, VLOSS, JSC) of all the compounds to reveal the influence of halogen atomic substitution and π-extension at the end-capping on performance. The present investigation suggests viable strategies for further designing NFAs in OSCs.

Dual Interface Protection for High Performance and Excellent Long-Term Stability of Organic Solar Cells.

Stability is still the main barrier to the commercial application of organic solar cells (OSCs), although the maximal power conversion efficiency (PCE) value has exceeded 19%. The encapsulation technique is an effective and vital way to guarantee the long-term stabilities of OSCs, but it can only avoid the penetration of water and oxygen from the environment. Herein, we introduced a structure that provides dual interface protection by using commercially available and chemically stable polyvinylidene fluoride (PVDF) as the cathode interface protection layer working as the cathode interlayer (CIL) and poly(styrene-comethyl-methacrylate) (PS-r-PMMA) as the anode interface protection layer between the poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) and the active layer. With this structure, both the migration of impurities caused by degradation of the interfacial layer and the infiltration of oxygen and water in the air can be prevented. PVDF can effectively provide optimal electron transfer by improving the surface potential of active layers and lowering the work function of the Al electrode. PS-r-PMMA can improve the hydrophobicity of PEDOT:PSS and induce optimized phase separation, facilitating charge transfer. After storage in an air environment with a humidity of approximately 60% for 3600 h, the device based on the PM6:IT-4F blend film with dual interface protection showed a decrease in its PCE value from 13.43 to 10.90%, retaining 81.2% of its original PCE value, in contrast to the sharp decrease in the PCE value from 13.66 to 0.74% of the device without dual interface protection. The dual interface protection design could also be useful in the high-performance PM6:Y6 system, which shows a champion PCE of 15.39% and shows potential for the effective fabrication of stable OSCs in the future.

Theoretical modelling of novel indandione-based donor molecules for organic solar cell applications

The development of efficient hole transport materials (HTMs) are highly attractive for the photovoltaic community to further improve the power conversion efficiency (PCE) and stability of organic solar cells. Therefore, in the present study, we have designed six new (H3T1-H3T6) small-molecule based HTMs for bulk-heterojunction (BHJ)-OSC. The photophysical characteristics and optoelectronic characterizations are systematically investigated. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) are employed to study the arrangement of frontier molecular orbitals (FMOs), optical characteristics, open-circuit voltages, density of states, transition density matrix, and reorganization energies of holes and electrons. The designed materials (H3T1-H3T6) have shown a better absorption phenomenon that ranges maximum up to ∼563.00 nm and offering optical band gap at ∼2.10 eV. Additionally, all the designed materials have displayed a well-matched HOMO along with higher LUMO energy levels regarding PC61BM molecule. The calculations of H3T-2/PC61BM provide a deep insight about the charge shifting at the donor-acceptor (D-A) interface. The results of these theoretical characterizations have shown that an efficient molecular designing and strategy are prerequisite to get a desirable photovoltaic precursor best fitted for BHJ-OSCs. Thus, these modelled materials (H3T1-H3T6) are being suggested for synthesis and future development of efficient organic solar cell devices.

A GIWAXS study of crystallization in annealed conjugated polymers presenting technological interest for organic solar cell applications

A GIWAXS study of crystallization in annealed conjugated polymers presenting technological interest for organic solar cell applications

Electron-deficient TVT unit-based D–A polymer donor for high-efficiency thick-film OSCs

As the power conversion efficiencies of organic solar cells (OSCs) have been improved continuously in recent years, more attention will be paid to the industrial production and practical application of OSCs. However, there are still many problems to be solved in the process of large-scale production. Among them, reducing the costs of the materials and enhancing the film-thickness tolerance of the active layer are the two key points. Therefore, it is urgent to develop organic semiconductor materials which are easy to synthesize and suitable for the construction of high-efficiency, thick-film OSCs. In this work, we have focused on the (E)−2-[2-(thiophen-2-yl)vinyl]thiophene (TVT) unit because of its unique coplanar structure. And we noticed that TVT was mostly used as an electron-donating unit in the previous reports. However, we have modified TVT into electron-withdrawing unit by the introduction of fluorine atoms/ester groups. And two new donor–acceptor (D–A) copolymers have been obtained by combining the electron-withdrawing TVT unit with benzo[2,1-b:4,5-b′]dithiophene (BDT) unit. Among them, the polymer based on the ester modified TVT unit presents excellent photovoltaic performance by virtue of its good solubility and preferable molecular stacking mode, and the corresponding devices also show extraordinarily high-thickness tolerance. The emergence of this new electron-withdrawing TVT unit will undoubtedly further promote the development of low-cost, high-efficiency, thick-film OSCs.

Controllable Photoelectric Properties of Carbon Dots and Their Application in Organic Solar Cells

Controllable Photoelectric Properties of Carbon Dots and Their Application in Organic Solar Cells