Sb₂Se₃ planar solar cells with over 10.5% efficiency have been achieved by a novel additive-assisted chemical bath deposition (CBD) technology, in which the kinetics of the deposition can be elaborately regulated via the use of additives.

Highly aligned Cu₂O, Cu₂O/CuO, Cu₂O/CuO/TiO₂ and Cu₂O/TiO₂ nanowires arrays on Au substrates were prepared by controlled air annealing of the electrodeposited Cu nanowires and furthered with dip coating. Photoelectrochemical investigations were carried out to determine their potential as photocathodes for water photo-reduction. The photocurrent of the Cu₂O nanowires photocathode was found to be twice that of the Cu₂O film, largely due to the higher surface area and the shorter carrier diffusion length associated with the nanowires array configuration. However, the bare Cu₂O nanowires suffered from a significant photo-induced reductive decomposition with the electronic state of copper transferred from Cu(I) to Cu(0). By modifying the surface of the Cu₂O nanowires with protecting layers of CuO and TiO₂, direct contact of Cu₂O with the electrolyte was avoided and the Cu₂O/CuO/TiO₂ coaxial nanocable structures were found to gain a 74% higher photocurrent and 4.5 times higher stability, compared with the bare Cu₂O nanowires array. To understand the mechanism of the improved performance, a detailed characterization and analysis on the structure, circuitry and band alignment for the Cu₂O/CuO/TiO₂ configuration was carried out. The present study suggests a promising nanostructured photocathode configuration, which can lead to a large photocurrent with good stability against photocorrosion.

Recent efforts to improve the performance of photocathodes for hydrogen evolution are reviewed.

In this work, photoluminescence (PL), admittance spectroscopy (AS) and drive-level capacitance profiling (DLCP) were performed to analyze the defect properties of a Cu₂ZnSnS₄ (CZTS) solar cell. Compared to a high efficiency CuInGaSe₂ (CIGS) solar cell, the absorber of the CTZS device has larger potential fluctuation which can be attributed to the co-existence of a high concentration of deep acceptor (Cu_Zn) and deep donor (Zn_Cu) defects. The density of the interface states in the CZTS device is also orders higher than that in the CIGS device. These high density defects (both in the bulk and at the CZTS/CdS interface) will induce a large loss in the open-circuit voltage (V_oc), resulting in a lower performance of the CZTS device. We suggest that defect control can be a possible solution to reduce the potential fluctuation induced by acceptors. To overcome the potential fluctuation induced trapping effect for electrons by the Zn_Cu donors, a graded conduction band similar to CIGS will be good to eliminate electron localization.

This minireview comments on the development and potential impact of perovskite solar cells on the solar cell family.