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In this work, we designed a series of butterfly type organic dyes, named ME07 - ME13 by introducing such as triphenylamine, phenothiazine, coumarin groups etc. as electron donors and further investigated their absorption spectra using density functional theory (DFT) and time-dependent DFT (TDDFT). All designed dyes cover the entire visible absorption spectrum from 300 to 800 nm. It's fascinating that ME13 molecule has two absorption peak and the molar coefficient of two absorption peaks are above 4.645 × 10 4 M −1 ·cm −1 . The light absorption area of ME13 exhibits an increment of 16.5–19.1% compared to ME07 - ME12 . Furthermore, we performed a detailed analysis on their geometrical and electronic properties, including molecular structures, energy levels, light harvesting efficiency (LHE), driving force (ΔG inject ), regeneration (ΔG regen ),electron dipole moments (μ normal ), intermolecular electron transfer and dye/(TiO 2 ) 38 system electron transitions. The results of calculation reveal that double coumarin donors in ME13 are promising functional groups for butterfly type organic dye sensitizers. It is expected that the design of double donors can provide a new strategy and guidance for the investigation in high efficiency dye-sensitized devices. [ABSTRACT FROM AUTHOR]

Based on the experimentally synthesized dye JZ145 , we designed a series of novel D-A-π-A dyes SPL201-SPL211 with different π-conjugated bridges and a new auxiliary withdrawing group for highly efficient dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent DFT(TDDFT). The molecular structures, energy levels, absorption spectra, light-harvesting efficiency (LHE), driving force of injection(ΔG inj ) and regeneration(ΔG reg ) , electron dipole moment (μ normal ) and lifetime of the first excited state(τ) were all scrutinized in details. Results reveal that the additional withdrawing group A2 and the π-conjugated group di-η-hexyl-substituted cyclopentadithiophene (CPDT) are more promising functional groups for the organic dyes with D-A-π-A structure. We further designed SPL212 and SPL213 by employing indoline group as donor, the above screened functional groups as π-conjugated bridge and additional withdrawing group, biscarbodithiolic acid and dicyanovinyl sulfonic acid groups as acceptor group. We found that SPL212 exhibits not only a higher molar extinction coefficient with an increment of 30.8%, larger excited state lifetime and an obvious redshift of 201 nm but also a broader absorption spectrum covering the entire visible range even up to near-IR of 1200 nm compared to JZ145 . So, SPL212 can be used as a promising candidate for DSSCs. In addition, the results also prove that biscarbodithiolic acid may be more favorable than dicyanovinylsulfonic acid as acceptor group in DSSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Our ML model can efficiently predict the absorption spectrum of dye molecules. • Our ML model avoid the complex process in the DFT and experimental. The organic dye molecules have attracted significant attention due to their wide range of potential applications. However, the traditional method is time-consuming, while experimental synthesis methods involve complex processes. To streamline the performance evaluation process, we focus on predicting the absorption spectra of organic dyes without using excited states calculations. We built four prediction models of machine learning algorithms and used them to predict the absorption spectra of organic dyes. We obtained a machine learning model that can efficiently predict the absorption spectrum of dye molecules by optimizing the structure and energy level information of the ground state of dyes. [ABSTRACT FROM AUTHOR]

Laser dye molecules play an important role in tunable lasers due to enhancing the laser radiation intensity and increasing the laser adjustable range. The broad spectral bandwidth and visible light absorption allows for the evaluation of multiple fluorescence quenching mechanisms such as excition formation, photoinduced electron transfer, and excited-state proton transfer. A series of organic dye molecules (LD1-4 、 LA2-5 、 LU1-5 、 LV1-4 、 LI1-4) consisting of simple electron donor (D), conjugated bridge (π) and electron acceptor (A) units were designed using first-principles calculations in order to evaluate their potential for applications in tunable lasers. Furthermore, the optical and electronic properties of the dye molecules are analyzed in detail using density functional theory (DFT) and time-dependent density functional theory (TDDFT), including spectral parameters, energy levels and orbital contributions of organic dye molecules. The results indicate that LI1-3 show high molar extinction coefficient, visible light full color absorption and obvious red-shifted compared to the experimentally synthesized dye LA3. In particular, the newly designed LI3 exhibits not only a 190 nm red-shifted and a higher molar extinction coefficient with an increment of 19%, but also has an extremely broad absorption spectrum covering entire visible absorption spectrum from 380 to 750 nm compared to LD1. We also find that the dyes with dithiophene groups and naphthalene group as the electron donors are better absorption spectrum than dyes with double bond group and benzene group. These calculated results will hopefully contribute to the further development of novel laser dye molecules and further provide scientific support and theoretical guidance for subsequent related research. Image 1 • A rational and efficient dyes design approach is developed. • Provide a proof of principle based on molecular fragment composition by in-silico. • Optimize the overall properties of the molecular by optimizing individual functional building blocks. [ABSTRACT FROM AUTHOR]