Facile Synthesis of Spherical TiO2 Hollow Nanospheres with a Diameter of 150 nm for High-Performance Mesoporous Perovskite Solar Cells

Investigation of Structural, Morphological, and Optical Properties of Novel Electrospun Mg-Doped TiO2 Nanofibers as an Electron Transport Material for Perovskite Solar Cells

Perovskite solar cells (PSCs) are quickly becoming efficient solar cells due to the effective physicochemical properties of the absorber layer. This layer should ideally be placed between a stable hole transport material (HTM) layer and a conductive electron transport material (ETM) layer. These outer layers play a critical role in the current densities and cell voltages of solar cells. In this work, we successfully fabricated Mg-doped TiO2 nanofibers as ETM layers via electrospinning. This study systematically investigates the morphological and optical features of Mg-doped nanofibers as mesoporous ETM layers. The existence of the Mg element in the lattice was confirmed by XRD and XPS. These optical characterizations indicated that Mg doping widened the energy band gap and shifted the edge of the conduction band minimum upward, which enhanced the open circuit voltage (Voc) and short current density (Jsc). The electron-hole recombination rate was lowered, and separation efficiency increased with Mg doping. The results have demonstrated the possibility of improving the efficiency of PSCs with the use of Mg-doped nanofibers as an ETM layer.

Ni-Doped SnO2 as an Electron Transport Layer by a Low-Temperature Process in Planar Perovskite Solar Cells

Perovskite solar cells (PSCs) based on a planar structure have recently become more attractive due to their simple manufacturing process and relatively low cost, while most perovskite solar cells employ highly porous TiO₂ as an electron transport layer in mesoporous devices offering higher energy conversion efficiency (PCE). In planar structural devices, non-radiative recombination effects of the absorber layer and the electron transport layer cause potential loss and lower PCE. We created an efficient electron transport layer by combining low-temperature Ni-doped SnO₂ with SDBS as a surfactant (denoted as Ni:SnO₂). Doping Ni⁺ into low-temperature solution-processed SnO₂ increased the power conversion efficiency of PSCs from 17.8 to 19.7%.

2D Slab Models of Nanotubes Based on Tetragonal TiO2 Structures: Validation over a Diameter Range

One-dimensional nanomaterials receive much attention thanks to their advantageous properties compared to simple, bulk materials. A particular application of 1D nanomaterials is photocatalytic hydrogen generation from water. Such materials are studied not only experimentally, but also computationally. The bottleneck in computations is insufficient computational power to access realistic systems, especially with water or another adsorbed species, using computationally expensive methods, such as ab initio MD. Still, such calculations are necessary for an in-depth understanding of many processes, while the available approximations and simplifications are either not precise or system-dependent. Two-dimensional models as an approximation for TiO2 nanotubes with (101) and (001) structures were proposed by our group for the first time in Comput. Condens. Matter journal in 2018. They were developed at the inexpensive DFT theory level. The principle was to adopt lattice constants from an NT with a specific diameter and keep them fixed in the 2D model optimization, with geometry modifications for one of the models. Our previous work was limited to studying one configuration of a nanotube per 2D model. In this article one of the models was chosen and tested for four different configurations of TiO2 nanotubes: (101) (n,0), (101) (0,n), (001) (n,0), and (001) (0,n). All of them are 6-layered and have rectangular unit cells of tetragonal anatase form. Results of the current study show that the proposed 2D model is indeed universally applicable for different nanotube configurations so that it can be useful in facilitating computationally costly calculations of large systems with adsorbates.

Effect of Poly(Titanium Oxide) on the Viscoelastic and Thermophysical Properties of Interpenetrating Polymer Networks

The influence of poly(titanium oxide) obtained using the sol-gel method in 2-hydroxyethyl methacrylate medium on the viscoelastic and thermophysical properties of interpenetrating polymer networks (IPNs) based on cross-linked polyurethane (PU) and poly(hydroxyethyl methacrylate) (PHEMA) was studied. It was found that both the initial (IPNs) and organo-inorganic interpenetrating polymer networks (OI IPNs) have a two-phase structure by using methods of dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The differential scanning calorimetry methods and scanning electron microscopy (SEM) showed that the presence of poly(titanium oxide) increases the compatibility of the components of IPNs. It was found that an increase in poly(titanium oxide) content leads to a decrease in the intensity of the relaxation maximum for PHEMA phase and an increase in the effective crosslinking density due to the partial grafting of the inorganic component to acrylate. It was shown that the topology of poly(titanium oxide) structure has a significant effect on the relaxation behavior of OI IPNs samples. According to SEM, a uniform distribution of the inorganic component in the polymer matrix is observed without significant aggregation.

Reduced Defects and Enhanced Performance of (FAPbI3)0.97(MAPbBr3)0.03-Based Perovskite Solar Cells by Trimesic Acid Additives

A high-quality organolead trihalide perovskite film with large-sized crystalline grains and smooth surfaces is required to obtain efficient perovskite solar cells (PSCs). Herein, high-quality (FAPbI₃)_0.97(MAPbBr₃)_0.03 perovskite films were fabricated using trimesic acid (TMA) additives in a halide perovskite precursor solution to obtain efficient PSCs. The X-ray diffraction analysis and scanning electron microscopy of the films revealed that the TMA had a significant effect on the roughness of the films by acting as a surface link, thus reducing the surface defects and recombination at the grain boundaries. In addition, with the addition of the TMA additive, a smooth perovskite film with a flat surface and no pinholes was obtained. The perovskite film was used to fabricate a PSC device, and the device exhibited a high power conversion efficiency of 17.26%, which was higher than that of the control device (15.15%) under the same conditions. This study demonstrates a facile method to passivate defects on the perovskite layer via surface modification.