Numerical optimization and performance evaluation of ZnPC:PC70BM based dye-sensitized solar cell

The increase in global energy consumption and the related ecological problems have generated a constant demand for alternative energy sources superior to traditional ones. This is why unlimited photon-energy harnessing is important. A notable focus to address this concern is on advancing and producing cost-effective low-loss solar cells. For efficient light energy capture and conversion, we fabricated a ZnPC:PC70BM-based dye-sensitized solar cell (DSSC) and estimated its performance using a solar cell capacitance simulator (SCAPS-1D). We evaluated the output parameters of the ZnPC:PC70BM-based DSSC with different photoactive layer thicknesses, series and shunt resistances, and back-metal work function. Our analyses show that moderate thickness, minimum series resistance, high shunt resistance, and high metal-work function are favorable for better device performance due to low recombination losses, electrical losses, and better transport of charge carriers. In addition, in-depth research for clarifying the impact of factors, such as thickness variation, defect density, and doping density of charge transport layers, has been conducted. The best efficiency value found was 10.30% after tweaking the parameters. It also provides a realistic strategy for efficiently utilizing DSSC cells by altering features that are highly dependent on DSSC performance and output.

Theoretical exploration of the forces governing the interaction between gold-phthalocyanine and gold surface clusters

Here we aim to explore the nature of the forces governing the adsorption of gold-phthalocyanine on gold substrates. For this, we designed computational models of metal-free phthalocyanine and gold-phthalocyanine deposited over a gold metallic surface represented by cluster models of different sizes and geometries. Thereby, we were able to determine the role of the metal center and of the size of the substrate in the interaction process. For this purpose, we worked within the framework provided by density functional theory, were the inclusion of the semi-empirical correction of the dispersion forces of Grimme's group was indispensable. It has been shown that the interaction between molecules and surfaces is ruled by van der Waals attractive forces, which determine the stabilization of the studied systems and their geometric properties. Their contribution was characterized by energy decomposition analysis and through the visualization of the dispersion interactions by means of the NCI methodology. Moreover, calculations of Density of States (DOS) showed that the molecule-surface system displays a metal-organic interface evidenced by changes in their electronic structure, in agreement with a charge transfer process found to take place between the interacting parts.

Fragmentation and slow autoneutralization of isolated negative molecular ions of phthalocyanine and tetraphenylporphyrin

Macrocyclic tetrapyrrolic compounds, such as naturally occurring or artificial porphyrins and phthalocyanines, have unique and highly attractive properties for applications in medicine and technology. The interaction of free-base phthalocyanine (H₂Pc) and tetraphenylporphyrin (H₂TPP) molecules with low-energy (0-15 eV) electrons was studied in vacuo by means of negative ion resonant electron capture mass spectrometry. Close similarities in formation and decay of negative ions of these compounds were revealed. Efficient formation of long-lived molecular negative ions (MNIs) was observed in the incident electron energy range of 0-8 eV, unprecedentedly wide for organic compounds and comparable to the range characteristic to carbon atomic clusters, fullerenes. Experiments testify to the strong persistence of MNIs of both compounds to dissociative decay, isomerization, and electron autodetachment. Lifetimes of MNIs as a function of incident electron energy were measured and it was concluded that the isolated anions may retain additional electrons in a time scale of up to hundreds of seconds at standard temperature due to the high adiabatic electron affinity of these large molecules. For the representatives of dyes and photochromic compounds comprehensively studied in terms of interaction with light, the present work highlights yet another unique property of these molecules, namely the capability to attach and durably retain an additional electron of low, pre-ionization energy.