Metal complex as p-type dopant-based organic spiro-OMeTAD hole-transporting material for free-Li-TFSI perovskite solar cells.

Lithium bis(fluorosulfonyl)imide (Li-TFSI) is an efficient p-dopant that has been used to enhance the conductivity of perovskite solar cells (PSCs). However, the performance of the corresponding devices is still not satisfactory due to the impact of Li-TFSI on the fill factor and the short-circuit current density of these PSCs. Herein, a new Mn complex [(Mn(Me-tpen)(ClO4)2-)]2+ was introduced as a p-type dopant into spiro-OMeTAD and was successfully applied as a hole transport material (HTM) for PSCs. Analytical studies used for device characterization included scanning electron microscopy, UV-Vis spectroscopy, current-voltage (IV) characteristics, incident photon to current efficiency, power conversion efficiency (PCE), and electrochemical impedance spectroscopy. The UV-Vis spectra displayed oxidation in the HTM by the addition of a dopant. Moreover, the movement of electrons from the higher orbital of the spiro-OMeTAD to the dopant stimulates the generation of the hole carriers in the HTM, enhancing its conductivity with outstanding long-term stability under mild conditions in a humid (RH ∼ 30%) environment. The incorporation of the Mn complex into the composite improved the material's properties and the stability of the fabricated devices. The Mn complex as a p-type dopant for spiro-OMeTAD exhibits a perceptible PCE of 16.39% with an enhanced conductivity of 98.13%. This finding may pave a rational way for developing efficient and stable PSCs in real environments.

Effect of light on concomitant sequestration of Cu(II) and photodegradation of tetracycline by H-MOR/H-ß/H-ZSM5 zeolites.

It is important that a pollution remediation system be able to cater for a variety of pollutant species present in the water to be treated. The aim of this study was to utilise a series of commercial zeolites (H-MOR, H-ß, and H-ZSM5) for the concomitant adsorption and photodegradation of Cu2+ and tetracycline (TC) molecules. The adsorbent cum photocatalyst was characterised by SEM and FTIR. FTIR confirmed the key functional groups (Si-O-Si and Al-O-Si) in the series of zeolites, and H-ß zeolite was demonstrated to be the most effective adsorbent cum photocatalyst for both adsorption and photodegradation of Cu2+ and TC molecules. These results were further corroborated from the pseudo-first-order rate constant values. Among the investigated zeolites, H-ZSM5 displayed the least adsorption and photodegradation performance for Cu2+ and TC molecules. The photolysis reaction confirms the significant role of zeolites in the photodegradation test, as low performance was recorded in the absence of the zeolites.

Photocatalytic remediation of methylene blue using hydrothermally synthesized H-Titania and Na-Titania nanotubes.

Although nanotube is among the most effective morphology of Titania due to its unilateral pathway for photo-generated charge transfer and mechanical stability, its performance is still hampered by high recombination. In the present study, to further improve the photocatalytic degradation performance of Titania, univalent elements of H and Na were respectively ion-exchanged into the Titania nanotubes (TNTs). The photocatalyst was characterized using XRD, TEM, ICP-AES, and FTIR. The modified samples displayed enhanced photocatalytic degradation performance over Degussa TiO2 under UV-A light illumination of MB. The rate constants of NaTNT and HTNT were 16 and 13 times that of Degussa TiO2. Specifically, the Na-TNTs showed better photocatalytic degradation activity than H-TNTs with a rate constant of 0.12 min-1 while the latter showed 0.09 min-1. The optimum adsorption and photocatalytic performance of NaTNT were determined at pH 6 achieving about 99% MB removal within 10 min of irradiation. The ion exchange NaTNT displayed excellent reusability after the fifth cycle of the photocatalytic tests and superoxide radicals were experimentally determined to be the main reactive oxygen species involved in the photocatalytic degradation of MB.

An organic hole-transporting material spiro-OMeTAD doped with a Mn complex for efficient perovskite solar cells with high conversion efficiency.

2,{2}',7,{7}'-Tetrakis(N,N-di-p-methoxyphenylamine)-9,{9}'-spiro-bi-fluorene(spiro-OMeTAD) has often been used as a hole-transporting material (HTM) in mesoscopic perovskite solar cells (PSCs). However, its potential applications are limited due to its poor conductivity of approximately 10-6 to 10-5 cm2 V s-1 in pristine form, and this influences the stability and intrinsic hole conductivity of the device. In this work, a Mn complex [(Mn(Me-tpen)(ClO4)2 -)]2+ is introduced as a p-dopant to improve the properties of spiro-OMeTAD-based PSCs, including the optical, electrical, conductivity, and stability properties. Interestingly, the use of spiro-OMeTAD with an optimum concentration (1.0% w/w) of Mn complex in mesoscopic PSCs achieves a remarkable power conversion efficiency of 17.62% with a high conductivity of 99.05%. Spiro-OMeTAD with Mn complex as a p-dopant under UV-vis spectroscopy shows a different peak at 520 nm, confirming that oxidation occurs upon the addition of the Mn complex. The enhanced efficiency of the PSCs may be attributed to an increase in the optical and electrical properties of the HTM in the spiro-OMeTAD doped Mn complex.