Organic Dye-sensitized Solar Cells Research Articles

Molecular Design and DFT Analysis of High-performance Dyes Based on Pyrene with Different Donor Parts and Their Optoelectronic Applications.

The performance and efficacy of dyes, which are crucial photon-harvesting components in dye-sensitized solar cells (DSSCs), must be meticulously analysed at the molecular level. This research focuses on a theoretical investigation of dye characteristics rather than the synthesis of novel compounds. Using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT), we have analysed six D-π-A structure dyes designed with pyrene as the π-bridge and various functional groups as donors. Our study examines their geometrical, electronic, optical, electronic localization, and electrochemical properties. The findings reveal that these theoretically designed D-π-A dyes show significant improvements in light-harvesting efficiency, open-circuit photovoltage, electron injection efficiency, and overall photovoltaic performance. The analysis indicates effective electron injection from each dye into the conduction band of TiO2, followed by efficient regeneration and enhanced intra- and intermolecular charge transfer properties. The incorporation of pyrene as a π-bridge and the use of different functional groups as donors are crucial for facilitating electron transfer from the donor to the acceptor region. Among the dyes studied, the D-π-D modified dye demonstrates superior theoretical performance, attributed to its higher energy levels of the lowest unoccupied molecular orbital and greater oscillator strengths for excited states. This results in improved intramolecular electron transfer and electron injection into the conduction band of TiO2, followed by effective regeneration. Overall, our study highlights the potential of these theoretically modeled dyes as highly promising sensitizers for DSSCs, due to their exceptional optical and electronic properties and impressive photovoltaic parameters. These findings position these molecular structures as strong candidates for future applications in organic DSSCs.

DFT and TD-DFT Investigations for the Limitations of Lengthening the Polyene Bridge between N,N-dimethylanilino Donor and Dicyanovinyl Acceptor Molecules as a D-π-A Dye-Sensitized Solar Cell.

One useful technique for increasing the efficiency of organic dye-sensitized solar cells (DSSCs) is to extend the π-conjugated bridges between the donor (D) and the acceptor (A) units. The present study used the DFT and TD-DFT techniques to investigate the effect of lengthening the polyene bridge between the donor N, N-dimethyl-anilino and the acceptor dicyanovinyl. The results of the calculated key properties were not all in line with expectations. Planar structure was associated with increasing the π-conjugation linker, implying efficient electron transfer from the donor to the acceptor. A smaller energy gap, greater oscillator strength values, and red-shifted electronic absorption were also observed when the number of polyene units was increased. However, some results indicated that the potential of the stated dyes to operate as effective dye-sensitized solar cells is limited when the polyene bridge is extended. Increasing the polyene units causes the HOMO level to rise until it exceeds the redox potential of the electrolyte, which delays regeneration and impedes the electron transport cycle from being completed. As the number of conjugated units increases, the terminal lobes of HOMO and LUMO continue to shrink, which affects the ease of intramolecular charge transfer within the dyes. Smaller polyene chain lengths yielded the most favorable results when evaluating the efficiency of electron injection and regeneration. This means that the charge transfer mechanism between the conduction band of the semiconductor and the electrolyte is not improved by extending the polyene bridge. The open circuit voltage (VOC) was reduced from 1.23 to 0.70 V. Similarly, the excited-state duration (τ) decreased from 1.71 to 1.23 ns as the number of polyene units increased from n = 1 to n = 10. These findings are incompatible with the power conversion efficiency requirements of DSSCs. Therefore, the elongation of the polyene bridge in such D-π-A configurations rules out its application in solar cell devices.

Combined experimental and DFT investigation on photovoltaic performance of low-cost metal-free organic dye-sensitized solar cells

Metal-free organic dyes, viz. eosin yellow (eosin-Y), fluorescein and curcumin were used as sensitizers in zinc oxide (ZnO) nanoparticles thin film photoanode based dye-sensitized solar cell (DSSC) and also investigated by density functional theory (DFT). UV–vis spectrophotometer was employed to determine absorption feature of dyes in solar spectrum, adsorption tendency towards ZnO photoanode surface, molar-extinction coefficient and desorbed dye molecules from the photoanode surface. The photovoltaic performance of metal-free organic DSSCs employing imidazole based liquid electrolyte and platinum counter electrode was evaluated under standard light exposure of 85 mW/cm2. Among the dyes, eosin-Y DSSC delivered overall energy conversion efficiency (η) of 0.95 % with short-circuit photocurrent density (Jsc) of 2.98 mA cm−2, open-circuit photovoltage (Voc) of 0.54 V and fill factor (FF) of 0.50, which was about 20 % and 40 % higher than that of the energy conversion efficiency of DSSCs sensitized with fluorescein and curcumin dyes, respectively. The better photovoltaic performance exhibited by the eosin-Y DSSC is credited to its high molar extinction coefficient, intense light absorption in the solar spectrum and good adsorption on ZnO thin film photoanode surface. The maximum driving force for dye molecules regeneration and electron injection value of eosin-Y dye attached on the surface of ZnO cluster (eosin-Y + ZnO) resulted in higher Voc. The outcomes of this experimental data are in well agreement with DFT results.

5-(9-(p-Tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazol-6-yl)thiophene-2-carbaldehyde

Donor–π spacer–acceptor (D–π–A) dyes are among the most attractive structures for the design of organic dye-sensitized solar cells (DSSCs). Typically, the key intermediates for these sensitizers are D–π compounds containing an aldehyde group to which an anchor acceptor group is attached via the Knoevenagel reaction. In this communication, 5-(9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazol-6-yl)thiophene-2-carbaldehyde was prepared via the Suzuki cross-coupling reaction. The structure of the newly synthesized compound was established by means of high-resolution mass spectrometry, 1H NMR, 13C NMR, IR, and UV–Vis spectroscopy. The title compound would be used in the synthesis of sensitizers for DSSCs.

Minimization of Photovoltage Loss of Iodine Electrolytes by Ethylene Carbonate and PAN-Based Block Copolymer for High-Performance Quasi-Solid-State Organic Dye-Sensitized Solar Cells

Minimization of Photovoltage Loss of Iodine Electrolytes by Ethylene Carbonate and PAN-Based Block Copolymer for High-Performance Quasi-Solid-State Organic Dye-Sensitized Solar Cells

1,2,4-Triazine-based Materials: Spectroscopic Investigation, DFT, NBO, and TD-DFT Calculations as Well As Dye-sensitized Solar Cells Applications

In this manuscript, we report four series for 1,2,4-triazine derivatives as dye-sensitized solar cells (DSSCs). Density functional theory (DFT) methods via utilizing Becke's three-parameter functional and LeeeYangeParr functional (B3LYP) level with 6-31G (d, p) basis set to investigate their modeling molecular structures. Optimized molecular structures for studied molecular structures are obtained using the DFT/B3LYP/6-31G (d, p) method. In addition, the time-dependant density functional theory (TD-DFT) is used to study the optoelectronic properties and absorption spectra using DFT/CAM-B3LYP/ 6-31G + + (d, p) level in the Gaussian 09 program. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap (Eg), light harvest efficiency (LHE), and open-circuit voltage (Voc) of the studied molecular structures are calculated and illustrated. These properties indicate that these molecular modeling structures as good candidates for utilization in organic DSSCs.

The effect of Clathrin protein addition on increasing the number of electrons in organic Dye-Sensitized Solar Cell (DSSC)

Dye-Sensitized Solar Cell (DSSC) is a solar cell that uses dyes to convert sunlight into electricity, which has a wide absorption spectrum, is inexpensive and environmentally friendly. Visible light sensitive dyes are used in Dye-Sensitized Solar Cell (DSSC) types to generate electricity. Natural sensitive dyes that are commonly used in DSSC are chlorophyll derived from plants. Chlorophyll is a source of electrons which will be excited when exposed to light, resulting in an electric current in the DSSC. The most basic problem in Dye-Sensitized Solar Cell (DSSC) is that the number of electrons produced is still lower than that of silicon solar cells. This is due to the high recombination process of free electrons due to limited diffusion of electrons trapped at the boundary between TiO2 particles caused by less than optimal contact between particles. Clathrin is a protein that plays an important role in the formation of the vesicle layer which is responsible for the transport of molecules in cells. As a protein that plays an important role in the cell transport system, Clathrin can bind to ions in order to transport cells. This study has proven that the addition of Clathrin protein to the DSSC layer can increase the number of electrons generated in the DSSC. The method used in this study was to vary the addition of Clathrin content to TiO2, namely the Clathrin concentration of 0 %, 25 %, 50 % and 75 %. The results showed that increasing the Clathrin content would increase the electric current and the number of electrons generated by the DSSC, namely the 75 % Clathrin content with an electric current of 5,247 mA and the number of electrons was 3.28x1016

New organic dye-sensitized solar cells based on the D-A-π-A structure for efficient DSSCs: DFT/TD-DFT investigations.

Global energy consumption has increased due to population growth and economic development. Solar energy is one of the most important renewable energy sources for human consumption. In this research, four novel organic dyes (D2-D5) of the D-A-π-A structure based on triphenylamine (TPA) were studied theoretically using DFT and TD-DFT techniques for future usage as dye-sensitized solar cells (DSSCs). The effects of modifying the π-spacer of the reference molecule D1 on the structural, electronic, photovoltaic, and optical characteristics of the D2-D5 dyes were studied in detail. D2-D5 exhibited band gaps (E gap) in the range from 1.89 to 2.10 eV with λ abs in the range of 508 to 563 nm. The results obtained show that modifying the π-spacer of the dye D1 increased its hole injection and reinforced the intramolecular charge-transfer (ICT) impact, which resulted in a red-shifted ICT absorption with a greater molar extinction coefficient. The theoretically calculated open-circuit voltage (V oc) values ranged from 0.69 to 1.06 eV, while the light-harvesting efficiency (LHE) values varied from 0.95 to 0.99. Indeed, this theoretical research could guide chemists to synthesize effective dyes for DSSCs.

Quantum chemical calculations of phenazine-based organic dyes in dye-sensitized solar cells

Abstract In this study, quantum chemical calculations of phenazine-based organic molecules applied in organic dye-sensitized solar cells (DSSCs) have been made and interpreted. Since DSSC molecules work with the electron push–pull system, the sequence of other compounds (2–8) from compound 1 is designed as a donor–π bridge (weak acceptor)–acceptor (D–π–A). Later, the studied molecules were expanded from 2a to 8c by lengthening the conjugation with phenyl, thiophene, and furan to the acceptor parts. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are practiced to investigate all structures and absorption spectra of molecules, respectively. It has been observed that the phenazine-based molecule series are good candidates for DSSCs, both with their band gap and their absorption spectrum results. It can be assumed that changing the HOMO and LUMO energy values of all designed structures according to compound 1 can absorb light in the organic dye-sensitized solar cells and transfer electrons to the conductivity band of TiO2. As a result, it has been resolved that various dyes can be designed for dye-sensitizing solar cells by calculating electronic energies, HOMO–LUMO energies, and absorption wavelengths.

A Brief Review on Dye Sensitized Solar Cells

Photo-voltaic (PV) devices such as a Dye-Sensitized Solar Cell (DSSC) is a source of energy that converts incident photon or solar radiation to usable electricity. DSSCs are fast becoming a viable and interesting alternative to the traditional inorganic photo-voltaic devices to address the demerits of the inorganic PV devices like the use of expensive noble metals and high-cost chemical synthesis processes. A DSSC functions with two main components, i.e., a photo-sensitizer that absorbs incident light and a semiconductor onto which it is adhered to and a conductive glass housing such as Florine-doped Tin Oxide (FTO) or Indium-doped Tin Oxide (ITO), between which the sensitizer, semiconductor and an electrolyte are sandwiched. The semiconductor is preferably a wide-band semiconductor, of which the commonly used semiconductors in a DSSC are made of a nanoparticle layer of Titanium dioxide (TiO2), Zinc oxide (ZnO) and Tin oxide (SnO2). The utility of these solar cells with a diverse number of natural photo-sensitizers for use as an alternative PV device is described. Currently, there are an abundance of natural sources that could be used to obtain photo-sensitizers from, such as, micro and macro algae, plants, bacteria, etc. leading to increased importance in renewable energy sector and has gained traction to be a viable renewable energy resource. In addition to the functioning of an organic DSSC, various characteristics of the pigments used as photo-sensitizers are described here. Patents filed regarding eco-friendly and natural Dye-Sensitized Solar Cells have been increasing as of late and holds substantial promise.

Tuning the charge transfer and optoelectronic properties of tetrathiafulvalene based organic dye-sensitized solar cells: a theoretical approach.

Here, we have designed a series of dyes following the donor–π–acceptor (D–π–A) architecture by incorporating tetrathiafulvalene (TTF) as the donor unit and phthalazine (PTZ), diketopyrrolopyrrole (DPP) and quinoxaline (QNX) as the acceptor units, along with the thiophene unit as a π-bridge. The designed dyes have been designated as TTF-PTZ, TTF-DPP and TTF-QNX respectively. We have used cyanoacrylic acid as the anchoring group for the dyes TTF-PTZ and TTF-DPP, while for the third dye, TTF-QNX, we used a carboxylic group. The structural, electronic and photochemical properties of the designed dyes are investigated under the regime of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. In this regard, the dihedral angle, energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), energy difference between the HOMO and LUMO (ΔH–L values), partial density of states (PDOS), ground state oxidation potential (GSOP), excited state oxidation potential (ESOP), ionization potential (IP), electron affinity (EA), molecular electrostatic potential surface (MEPS) analysis, reorganization energy (λ), electronic coupling matrix element (V), charge transfer rate (kCT), hopping mobility (μhop), absorption spectra, exciton binding energy (EBE) and electron density difference (EDD) of the designed dyes are calculated. This study reveals that the dyes TTF-DPP-4 and TTF-DPP-6′ exhibit the lowest ΔH–L values. The study also reveals that the attachment of the –NH2 group at the donor unit and the –NO2 and –CF3 groups at the acceptor units lower the ΔH–L values of all of the designed dyes. We have also observed that the GSOP of all the designed dyes lie below the redox potential of the I−/I3− electrolyte couple. However, the ESOP of the TTF-PTZ and TTF-QNX groups of dyes, along with the most of the dyes belonging to the TTF-DPP group, lie above the conduction band of the TiO2 semiconducting surface. Moreover, the total reorganization energy (λtot) values are low for the TTF-DPP and TTF-QNX groups of dyes, which confirm the better electron–hole separation efficiency in these groups of dyes. Furthermore, the absorption properties of the designed dyes indicate that the TTF-DPP groups of dyes possess the maximum absorption wavelength (λmax) values and attachment of the –CH3 group at the donor part increases the electron density of the dyes, which in turn results into the maximum red-shift. Therefore, the study reveals that the designed dyes are likely to exhibit facile charge transport. Moreover, the electronic properties of the dye–TiO2 clusters strengthen the performance of the dyes compared to those of the isolated dyes. Hence, our study provides good recommendations for the further design of dyes to enhance the performance of dye-sensitized solar cells (DSSCs).

Synthesis and characterization of TiO2/ZnO-Ag@TiO2 nanocomposite and their performance as photoanode of organic Dye-Sensitized Solar Cell

DSSC is one of the most promising energy conversion devices. A new scheme of TiO2/[email protected]2 multilayer nanocomposite was introduced as the working layer of organic DSSC. TiO2, as an inert material, was used to encapsulate Ag and applied as the photoanode. ZnO and [email protected]2 nanoparticles were synthesized using co-precipitation and one-pot synthesized method, respectively. The best photovoltaic parameter was performed by the highest fraction of [email protected]2 with the energy gap of 3.14 eV. It was appropriate that the energy gap of the films decreased as [email protected]2 continued to increase, thus it was influenced their photovoltaic performance.

Enhanced performance of dye-sensitized solar cell with thermally stable natural dye-assisted TiO2/MnO2 bilayer-assembled photoanode

This study reports the performance analysis of an organic dye-sensitized solar cell (DSSC), introducing MnO2 as an electron transport layer in TiO2/MnO2 bilayer assembly. The DSSCs have been fabricated using TiO2 and TiO2/MnO2 layer-by-layer architecture films onto fluorine-doped tin oxide (FTO) glass and sensitized with natural dye extracted from Malvaviscus penduliflorus flower in ethanol medium. The counter electrode was prepared to layer copper powder containing paste onto FTO's conductive side by the doctor's blade method. The optical, morphological, and structural properties of photoanodes were explored via ultraviolet–visible, field emission scanning electron microscopy, and X-ray diffraction analyses. Moreover, dye complexity and thermostability of dyes were characterized via Fourier-transform infrared spectroscopy and thermogravimetric analyses. The iodide/triiodide (i.e., I−/I3−) redox couple of electrolyte solution was employed as a charge transport medium between the electrodes. Finally, photoanode and counter electrode sandwiches were assembled to envisage the photovoltaic performance potential under simulated AM 1.5G solar illumination using 100 mW cm–2 light intensity. The as-fabricated DSSC comprising TiO2/MnO2 bilayer assembly exhibited 6.02 mA cm–2 short circuit current density (Jsc), 0.38 V open-circuit voltage (Voc), 40.38% fill factor, and 0.92% conversion efficiency, which is about 200% higher compared to the assembly devoid of MnO2 layer.

Promising architectures modifying the D-π-A architecture of 2,3-dipentyldithieno[3,2-f:2′,3′-h]quinoxaline-based dye as efficient sensitizers in dye-sensitized solar cells: A DFT study

As reported, (E)-2-cyano-3-(2,3-dipentyl-9-(7-(4-(p-tolyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indol-7-yl)benzo[c] (Cui and et al., 2019; He and et al., 2017; Feng and et al., 2013) [1,2,5]thiadiazol-4-yl)-5,6-dihydrodithieno[3,2-f:2′,3′-h]quinoxalin-6-yl)acrylic acid (DQ5) with D-A-π-A architecture was successfully synthesized, its electrochemical and photophysical properties were determined. It has a rigid dipentyldithieno[3,2-f:2′,3′-h]quinoxaline (DPQ) unit. DQ5, as a DPQ-based organic dye-sensitized solar cell, obtained an excellent power conversion efficiency of 7.12%. Based on this result, and in addition to DQ5, and to establish structure–property relationships, the electrochemical and photophysical properties, intramolecular charge transfer indices, reorganization energies, exciton binding energies and transition density matrix graphs in chloroform solvent of six new architectures derived from DQ5 were calculated using the DFT/and TDDFT/CPCM/BHandHLYP/6-31 + G(d,p). The new architectures included D-A-A-π-A (D1), D-A-D-π-A (D2), D-D-A-π-A (D3), D-D-D-π-A (D4), D-D-π-A (D5), and D-π-A (D6). The calculated results indicate that different architectures can modify the energy levels of HOMO and LUMO and ease intramolecular charge transfer and increase charge injection at the interface of dye/TiO2. The binding energies, electronic, and optical properties of the sensitizers@TiO2 cluster have also been explored. The light was shed on the electron/hole injection barrier and bandgap alignment as well. The sensitizers containing the D and/or A moiety, e.g., benzothiadiazole and/or benzo[c]thiophen showed larger binding energies than its absence in derivative, e.g., D6. Comprehensible intramolecular charge transfer was found in sensitizers before and after adsorption @TiO2 cluster in studied compounds. Different architectures derived from DQ5 can provide a new strategy to provide novel DPQ-based dyes and focus on the preparation of dyes with better performance.

Bridge effect on the charge transfer and optoelectronic properties of triphenylamine-based organic dye sensitized solar cells: theoretical approach

In this work, a series of six organic dyes-sensitized solar cells (DSSCs) combining various π-bridges with a fixed donor (triphenylamine) and a fixed electron acceptor (cyanoacrylic acid), namely D1-6, were studied. The geometrical structure, electronic and optical properties of these dyes have been investigated with the density functional theory and TD-BHandHLYP hybrid functional (time-dependent Becke-Half-and-Half-Lee–Yang–Parr’s) methods. The effects of π-bridging of the dyes have shown that the rings with a sulfur atom reduce the energy gaps and provide a redshift of the absorption spectra. Similarly, we focus on the description of the ground and excited state properties. On the other hand, the pyrrole group improves the open-circuit voltage (VOC) and the light-harvesting efficiency parameters leading to greater power conversion efficiency. Furthermore, the results revealed lowest total reorganization energy λ (λ+ and λ−) for the dye D3 with pyrrole linkage, which reflects its most favorable charge-transport properties, implying a lower charge recombination rate, faster charge injection and dye regeneration processes. Therefore, this study would provide a new path to design novel conjugated organic molecules as dyes for high-performance DSSCs.

Methodologies in Spectral Tuning of DSSC Chromophores through Rational Design and Chemical-Structure Engineering.

The investigation of new photosensitizers for Grätzel-type organic dye-sensitized solar cells (DSSCs) remains a topic of interest for researchers of alternative solar cell materials. Over the past 20 years, considerable and increasing research efforts have been devoted to the design and synthesis of new materials, based on “donor, π-conjugated bridge, acceptor” (D–π–A) organic dye photosensitizers. In this paper, the computational chemistry methods are outlined and the design of organic sensitizers (compounds, dyes) is discussed. With reference to recent literature reports, rational molecular design is demonstrated as an effective process to study structure–property relationships. Examples from established organic dye sensitizer structures, such as TA-St-CA, Carbz-PAHTDDT (S9), and metalloporphyrin (PZn-EDOT), are used as reference structures for an examination of this concept applied to generate systematically modified structural derivatives and hence new photosensitizers (i.e., dyes). Using computer-aided rational design (CARD), the in silico design of new chromophores targeted an improvement in spectral properties via the tuning of electronic structures by substitution of molecular fragments, as evaluated by the calculation of absorption profiles. This mini review provides important rational design strategies for engineering new organic light-absorbing compounds towards improved spectral absorption and related optoelectronic properties of chromophores for photovoltaic applications, including the dye-sensitized solar cell (DSSC).

Solution processed aligned ZnO nanowires as anti-reflection and electron transport layer in organic dye-sensitized solar cells

Aligned one-dimensional nanostructure-based solar cells have lower-performance than traditional dye-sensitized solar cells (DSSC); due to optical and electrical losses. In this letter, we minimized optical/electrical-loss by using low-temperature solution-processed ZnO nanowires (NW) as anti-reflection(AR)/electron-transport(ET) layer in newly designed indoline dye based-DSSCs. AR-layered organic-DSSC exhibit better durability performance and enhanced photocurrent density (Jsc), >26% compared to the bare devices; due to the enhanced light-coupling. Additionally, this letter debates the techniques to increase performance of the DSSCs in terms of current and voltage in detail. Such AR/ET layered architecture will be of broad academic and industrial interest, for example in photodetectors and so on.

13.6% Efficient Organic Dye-Sensitized Solar Cells by Minimizing Energy Losses of the Excited State

The electron-injection energy losses of dye-sensitized solar cells (DSSCs) are among the fundamental problems hindering their successful breakthrough application. Two triazatruxene (TAT)-based sensitizers, with one containing a flexible Z-type double bond and another a rigid single bond, coded as ZL001 and ZL003, respectively, have been synthesized and applied in DSSCs to probe the energy losses in the process of electron injection. Using time-resolved laser spectroscopic techniques in the kinetic study, ZL003 with the rigid single bond promotes much faster electron injection into the conductive band of TiO2 especially in the locally excited state (hot injection), which leads to higher electron density in TiO2 and a higher Voc. The devices based on ZL003 exhibited a champion power conversion efficiency (PCE) of 13.6% with Voc = 956 mV, Jsc = 20.73 mA cm–2, and FF = 68.5%, which are among the highest recorded results to date on single dye-sensitized DSSCs. An independent certified PCE of 12.4% has been obt...

Theoretical study of novel porphyrin D-π-A conjugated organic dye sensitizer in solar cells

In this study, the characteristic of the designed porphyrin sensitizer was studied by density functional theory (DFT) and time-dependent density functional theory (TDDFT). D-π-A sequence of seven donor-acceptor dyes A-F in the organic dye-sensitized solar cell (DSSCs) was analyzed. Firstly, the structure and frequency of porphyrin dyestuffs with different substituents were optimized by DFT method, and the structure and properties of the ground state of porphyrin dyes were studied by comparing the energy differences of different orbitals. Then, the TDDFT method was used to study the porphyrin molecules with different π bridge. The structure and properties of the excited state are discussed in terms of the energy and charge separation state of the molecular orbital of the porphyrin sensitizer. According to the absorption spectrum, the characteristic of the light absorption for the sensitizer molecule is investigated. The results shown that the key characteristic parameters closely related to the open circuit photovoltage (VOC) and the short circuit current density (JSC) of the porphyrin sensitizers helped to clarify different π bridges. The change of VOC and JSC affected the energy level change of the porphyrin sensitizers with different π bridge. Finally, a suitable π bridge was selected as a porphyrin sensitizer candidate with higher conversion efficiency.

Thienochrysenocarbazole based organic dyes for transparent solar cells with over 10% efficiency

Stable, transparent organic dye-sensitized solar cells were made with over 10% efficiencies.