Metal oxides are cheap, stable, non toxic, ubiquitous materials, and are therefore attractive for the use in a variety of devices, including photovoltaic cells. However, the short excited state lifetime of these materials, and the low speed at which electronic charge travels through them, makes them unsuitable for solar energy production. In an attempt to optimize the properties of metal oxides for solar energy conversion, BINA researchers have adopted a computational strategy. Specifically, they studied the complex electronic and photonic properties of iron oxide (a-Fe2O3) and cobalt oxide (Co3O4). We used density functional theory to predict the electronic structure (e.g. band gap) and the results were found to be in good agreement with experiment. Importantly, they have generated in-silico doped materials (e.g. Mg, Na, K) which were found to have enhanced electronic properties potentially making them suitable for photovoltaic use.

High photovoltage is an essential ingredient for the construction of a high efficiency quantum dot sensitized solar cell (QDSSC). In a recent study, BINA researchers presented a novel configuration of QDSSC which incorporates the photo-induced dipole (PID) phenomenon for improved open circuit voltage (V_oc). This configuration is based on a dipole moment which is created only under illumination. The generation of photo-dipoles was achieved by the creation of long-lived trapped holes inside a core of type-II ZnSe/CdS colloidal core/shell QDs, which are placed on top of the standard CdS QD sensitizer layer. Upon photo-excitation, the created photo-dipole negatively shifts the TiO₂ energy bands, resulting in a photovoltage which is higher by ~100 mV compared to the standard cell, without type-II QDs. This work provides new understanding regarding the operation mechanisms of photoelectrochemical cells, while presenting a new strategy for constructing high voltage QDSSCs. In addition, the PID effect has the potential to be implemented in other promising PV technologies.

Functionalized carbon nanostructures are a promising electrode material for future batteries and super-capacitors. Using a self-delaminating stack of thin catalytic films on a substrate, BIU researchers synthesized very large mats of carbon nanofibers (CNFs) using chemical vapor deposition (CVD). The yield obtained was over two orders of magnitude greater than that of substrate-bound CNF growth. This result outlined a new growth mechanism for catalysts not mechanically constrained by a substrate. Interestingly, the team obtained different morphologies when changing the substrate from which the catalyst stack delaminated. They plan to functionalize these structures and to test them as electrodes for batteries and super-capacitors.