Theoretical study on the efficiency of new organic dyes based on (E)-2-(2-(thiophen-3-yl)vinyl)-1,1′-bipyrrole as dye-sensitized solar cell sensitizers

Dye-sensitized solar cells (DSSCs) have gained critical importance as a leading emerging photovoltaic technology for low-cost power generation due to their simple production, light weight, applicability to the development of flexible photovoltaic devices, and use of abundant and inexpensive materials, including advantageous metal-free organic dyes. In this context, as a continuation of our work on DSSCs, a theoretical examination using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) was conducted to evaluate the photovoltaic performance of eight new organic dyes. Each dye contains an electron donor group ((E)-2-(2-(thiophen-3-yl)vinyl)-1,1′-bipyrrole), an electron acceptor group (cyanoacrylic acid (CCA)), and four auxiliary donor/acceptor groups, i.e., 3,4-ethylenedioxythiophene (EDOT), furan/benzothiadiazole (BTZ), diketopyrrolopyrrole (DPP) linked to π-conjugated bridges such as styrene or thiophene. We calculated several parameters for each dye, including EHOMO, ELUMO, Egap, λmax, Eex, pen-circuit photovoltage (VOC), light harvesting efficiency (LHE), regeneration driving force (ΔGreg), electron injection driving force (ΔGinject), and excitation lifetime (τ) to determine the photovoltaic efficiency of each dye. The results showed that the new dyes exhibited good performance and remarkable energy-conversion efficiencies. Additionally, all investigated dyes posed as promising candidates for the generation of effective DSSC sensitizers, particularly M6, which contained a styrene-linked EDOT auxiliary donor group.