Design and Development of D-A-D Organic Material for Solution-Processed Organic/Si Hybrid Solar Cells with 17.5% Power Conversion Efficiency

Organic/silicon hybrid solar cells have attracted much interest due to their cheap fabrication process and simple device structure. A category of organic substances, Dibenzothiophene-Spirobifluorene-Dithiophene (DBBT-mTPA-DBT), comprises dibenzo [d,b] thiophene and 3-(3-methoxyphenyl)-6-(4-methoxyphenyl)-9H-Carbazole, which function as electron donors. In contrast, methanone is an electron acceptor, with an ∆Est of 3.19 eV. This work focused on hybrid solar cells based on the guest-host phenomena of DBBT-mTPA-DBT and CBP. Using a Si/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) hybrid solar cell with an ultra-thin Dibenzothiophene-Spirobifluorene-Dithienothiophene (DBBT-mTPA-DBT) interlayer between Si and Al led to a PCE of 17.5 ± 2.5%. The DBBT-mTPA-DBT interlayer substantially improved the Si/Al interface, reducing contact resistance from 6.5 × 10⁻1 Ω·cm2 to 3.5 × 10⁻2 Ω·cm2. This improvement increases electron transport efficiency from silicon to aluminum and reduces carrier recombination. The solar cell containing the DBBT-mTPA-DBT/Al double-layer cathode shows a 10.85% increase in power conversion efficiency relative to the standard Al cathode device.

Transparent and Colorless Dye-Sensitized Solar Cells Exceeding 75% Average Visible Transmittance

Most photovoltaic (PV) technologies are opaque to maximize visible light absorption. However, see-through solar cells open additional perspectives for PV integration. Looking beyond maximizing visible light harvesting, this work considers the human eye photopic response to optimize a selective near-infrared sensitizer based on a polymethine cyanine structure (VG20-C x ) to render dye-sensitized solar cells (DSSCs) fully transparent and colorless. This peculiarity was achieved by conferring to the dye the ability to strongly and sharply absorb beyond 800 nm (S0-S1 transition) while rejecting the upper S0-S n contributions far in the blue where the human retina is poorly sensitive. When associated with an aggregation-free anatase TiO2 photoanode, the selective NIR-DSSC can display 3.1% power conversion efficiency, up to 76% average visible transmittance (AVT), a value approaching the 78% AVT value of a standard double glazing window while reaching a color rendering index (CRI) of 92.1%. The ultrafast and fast charge transfer processes are herein discussed, clarifying the different relaxation channels from the dye monomer excited states and highlighting the limiting steps to provide future directions to enhance the performances of this nonintrusive NIR-DSSC technology.

Towards developing efficient metalloporphyrin-based hybrid photocatalysts for CO2 reduction; an ab initio study

A series of thiophene-based donor-acceptor-donor (D-A-D) oligomer substituted metalloporphyrins (MPors) with different 3d central metal-ions (M = Co, Ni, Cu, and Zn) were systematically investigated to screen efficient hybrid photocatalysts for CO2 reduction based on density functional theory (DFT) and time-dependent DFT simulations. Compared with base MPors, the newly designed hybrid photocatalysts have a lower bandgap energy, stronger and broader absorption spectra, and enhanced intermolecular charge transfer, exciton lifetime, and light-harvesting efficiency. Then, the introduction of D-A-D electron donor (ED) groups into the meso-positions of MPors is a promising method for the construction of efficient photocatalysts. According to the calculated adsorption distance, adsorption energy, Hirshfeld charge and electrostatic potential analysis, it was revealed that CO2 physically adsorbed on the designed photocatalyst surface. In addition, among the studied model systems the ZnPor(ED)4 catalyst with four D-A-D electron donors exhibits the best photocatalytic performance due to its broadest absorption spectra with λmax = 500.12 nm and the highest adsorption energy of about 26 kJ mol-1. Finally, the sensing ability of the ZnPor(ED)4-based multi-terminal molecular junction for CO2 gas detection is determined using Green's functions. The transmission plots of this molecular junction are barely changed due to the physical adsorption of CO2 on the molecular surface, leading to the low sensitivity of the device. We believe that such a theoretical design can provide a general approach for further experimental and computational studies of photocatalysts used in the CO2 reduction process.

Simple adjustments to the molecular planarity of organic sensitizers: towards highly selective optimization of energy levels

Along with the specified planarization of molecular π-bridges, the LUMO levels of dyes can be effectively and selectively stabilized.