Organic Dyes with Hydrazone Moieties: A Study of Correlation between Structure and Performance in the Solid-State Dye-Sensitized Solar Cells

New metal-free organic dyes for solid-state dye-sensitized solar cells, employing a hydrazone fragment, have been synthesized and investigated. These sensitizers are obtained from relatively cheap starting materials, without the use of expensive catalysts, rigorously anhydrous or oxygen-free conditions. Correlation between the structure of hydrazone-containing dyes and the performance of the solid-state DSSC is investigated. The highest obtained solid-state device conversion efficiency, under standard AM 1.5G illumination (100 mW cm^–2), was 4.5% (<i>J</i>_SC = 8.03 mA cm^–2, <i>V</i>_OC = 880 mV, <i>FF</i> = 0.64)

Enhancing Thermal Stability and Lifetime of Solid-State Dye-Sensitized Solar Cells via Molecular Engineering of the Hole-Transporting Material Spiro-OMeTAD

Thermal stability of hybrid solar cells containing spiro-OMeTAD as hole-transporting layer is investigated. It is demonstrated that fully symmetrical spiro-OMeTAD is prone to crystallization, and growth of large crystalline domains in the hole-transporting layer is one of the causes of solar cell degradation at elevated temperatures, as crystallization of the material inside the pores or on the interface affects the contact between the absorber and the hole transport. Suppression of the crystal growth in the hole-transporting layer is demonstrated to be a viable tactic to achieve a significant increase in the solar cell resistance to thermal stress and improve the overall lifetime of the device. Findings described in this publication could be applicable to hybrid solar cell research as a number of well-performing architectures rely heavily upon doped spiro-OMeTAD as hole-transporting material

V‑Shaped Hole-Transporting TPD Dimers Containing Tröger’s Base Core

V-shaped hole transporting materials based on <i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetraarylbenzidine (TPD)-type moieties conjoined by Tröger’s base core were synthesized and investigated. These hole transporting materials were obtained by a three-step synthetic method, are fully amorphous, and demonstrate high glass transition temperatures and good thermal and morphological stability. Relatively high charge mobility (up to 0.036 cm² V ^–1 s^–1) was measured in these hole transporting materials, exceeding that of corresponding methyl and methoxy substituted TPD analogues without TB core by more than 2 orders of magnitude. Determined ionization potential and charge mobility values permit use of the synthesized compounds as hole transporting materials in fabrication of perovskite solar cells