• Energy Research

Abstract In recent years perovskite solar cells (PSC) is emerging as dominant technology among the photovoltaic world. The higher power conversion efficiency, facile deposition & fabrication techniques are making them favorable for many commercial purposes. Till now, the efficiency of 25.2% had been achieved for solid and up to 19.5% for flexible perovskite solar cells. This advancement in perovskite photovoltaic technology is achieved via massive research over the engineering of different layers of the device. Charge transporting layer (CTL) is one of the most important layers, its modification, deposition, passivation and optimization are the main challenges to be considered while experimenting. They are the interfaces among the contacts and the active layer, so, are crucial as they had to efficiently extract and transport the charges along with minimizing the traps between these layers. Here, the charge transporting layers based upon the nanomaterials of carbon and its derivatives are reported for different types of perovskite solar cells. These carbon-based nanomaterials not only enhance the power conversion efficiency and stability, but it also reduces the hysteresis loss. These materials include graphene-based materials, carbon nano tubes based and fullerene-based nanomaterials as CTL for perovskite solar cells. This review reports the use of carbon-based CTL in different forms for different types of perovskite solar cell applications.

A thermodynamic analysis of a half-effect absorption cooling system powered by a low-enthalpy geothermal source was carried out. This paper presents modeling of the half-effect absorption cooling system operating with an ammonia/lithium nitrate mixture and based on the first and second laws of thermodynamics, using as energy inputs real data from two geothermal wells located at Las Tres Vírgenes volcanic complex, Baja California Sur, México. Plots of coefficients of performance and exergy efficiency against condenser, evaporator, and generator temperatures are presented for the half-effect cooling system. The results showed that the system was able to operate at generation temperatures between 56 and 70 °C, which were supplied by the geothermal wells in order to produce cooling at temperatures as low as −16 °C, achieving coefficients of performance between 0.10 and 0.36, while the exergy efficiency varied from 0.15 to 0.40 depending on the system operating temperatures.

In this research, TiO2 nanotubes (NTs) were produced by electrochemical anodization of a Ti substrate where different NH4F wt.% in the electrolyte was added. NTs with diameter of 65–90 nm and 3.3–4.9 µm length were obtained and sensitized with binary cadmium chalcogenides nanoparticles, CdS and CdSe, by successive ionic layer adsorption and reaction method (SILAR). Additionally, both anions S and Se were deposited onto Cd, labeled as CdSSe and CdSeS, to evaluate the effect of the deposition order of the anion from the precursor solution to form cadmium chalcogenides. The structural, optical, and electrochemical performance were analyzed through the SEM, XRD, XPS, UV-VIS, lineal voltammetry and chronoamperometry characterizations. The increase of NH4F wt.% from 1.5% to 4.5% produced a decrement of the diameter and length attributed to the fluoride ions concentration causing solubility of the NTs. XRD confirmed the TiO2 anatase and hexagonal CdS structures. From the EDS and XPS results, the presence of small amount of Se in the sensitized samples demonstrated the doping effect of Se instead of forming ternary semiconductor. With the sensitization of the TiO2 NTs with the nanoparticles, an improved hydrogen generation was observed (reaching 1.068 mL h−1 cm−2) in the sample with CdSSe. The improvement was associated to a synergetic effect in the light absorption and higher cadmium chalcogenide amount deposited when sulfur ions were deposited before selenium.