Implications For Solar Cells Research Articles

Tailoring the Optical Properties of Selenium Nanoneedles by Pulsed Laser Ablation in Liquids: Implications for Solar Cells and Photocells

Tailoring the Optical Properties of Selenium Nanoneedles by Pulsed Laser Ablation in Liquids: Implications for Solar Cells and Photocells

Chemical Passivation of Crystalline Si by Al2O3 Deposited Using Atomic Layer Deposition: Implications for Solar Cells

Chemical Passivation of Crystalline Si by Al₂O₃ Deposited Using Atomic Layer Deposition: Implications for Solar Cells

Structures and Properties of Methylammonium Iodide Precursors of Halide Perovskites and Implications for Solar Cells: an Ab-Initio Investigation

Halide perovskite materials based on the prototypical CH3NH3PbI3 received much attention in recent years, with applications ranging from solar cells to light-emitting diodes. However, many fundamental aspects of the halide perovskite materials remain elusive at the moment, such as the structures and impacts of the methyl ammonium precursors on the halide perovskite properties. In this manuscript, we take one step back to theoretically investigate the monomer and dimer structures of methylammonium iodide, a precursor for the synthesis of the halide perovskite CH3NH3PbI3 via the first principles calculations, in order to provide a more complete view of the halide perovskite structures. The calculations show that the hydrogen bonds are found to be the major factor that stabilizes the methylammonium iodide monomers and dimers, while the dimeric structure exhibits geometry with each iodine atom shared by two neighbouring hydrogen atoms in the methylammonium cation molecules. The hydrogen bonds in the methylammonium iodide are proposed to be correlated with the three-dimensional halide perovskite buildup, and the formation of the hydrogen bond that is available in the halide perovskite framework could be “historically” traced back as early as the precursor preparation. The manuscript addresses the importance of the hydrogen bonds in the synthesis and the crystal formation of halide perovskite materials, and anticipates the necessity of the fundamental theoretical understanding of the structures from the halide perovskite precursors to the halide perovskite frameworks.

Influence of Radiation on the Properties and the Stability of Hybrid Perovskites.

Organic-inorganic perovskites are well suited for optoelectronic applications. In particular, perovskite single and perovskite tandem solar cells with silicon are close to their market entry. Despite their swift rise in efficiency to more than 21%, solar cell lifetimes are way below the needed 25 years. In fact, comparison of the time when the device performance has degraded to 80% of its initial value (T80 lifetime) of numerous solar cells throughout the literature reveals a strongly reduced stability under illumination. Herein, the various detrimental effects are discussed. Most notably, moisture- and heat-related degradation can be mitigated easily by now. Recently, however, several photoinduced degradation mechanisms have been observed. Under illumination, mixed perovskites tend to phase segregate, while, further, oxygen catalyzes deprotonation of the organic cations. Additionally, during illumination photogenerated charge can be trapped in the NH antibonding orbitals causing dissociation of the organic cation. On the other hand, organic-inorganic perovskites exhibit a high radiation hardness that is superior to crystalline silicon. Here, the proposed degradation mechanisms reported in the literature are thoroughly reviewed and the microscopic mechanisms and their implications for solar cells are discussed.

Ultrahigh vacuum preparation and characterization of TiO2/CdTe interfaces: Electrical properties and implications for solar cells

The semiconductor cadmium telluride (CdTe) has been grown in ultrahigh vacuum by standard molecular beam epitaxy on thin films of anatase titanium dioxide (TiO2) to investigate the interface properties of solid state injection type solar cells. These interfaces were studied by photoelectron spectroscopy and the band alignment was determined. The interface is characterized by a valence band offset ΔEV of 2.6 eV, a conduction band offset ΔEC of 0.7 eV, and a strong dipole δ of about 0.9 eV in contradiction to the electron affinity rule (Anderson model). Therefore this system is not very favorable for solar power generation.