Atomic Layer Deposition of an Sb₂Se₃ Photoabsorber Layer Using Selenium Dimethyldithiocarbamate as a New Se Precursor

Atomic layer deposition (ALD) of antimony selenide (Sb2Se3) is demonstrated using selenium dimethyldithiocarbamate as a new chalcogen precursor with tris­(dimethylamino) antimony as a metal source at 150 °C. The ALD chemistry with this organic-selenide precursor is explored as an alternative to highly toxic H2Se. The mechanistic facets of the reactions facilitating the deposition are revealed through theoretical investigations using the density functional theory. The findings from the theoretical study are in good agreement with the experimental findings. The deposition mechanism during the nucleation and linear growth regime is studied thoroughly with an in situ quartz crystal microbalance illustrating a “substrate-enhanced growth” during the initial deposition cycles. The saturated growth rate of ∼0.28 Å per cycle is achieved. The as-grown material is then investigated as the photon-absorber layer in the sensitized solar cell application. The charge transfer processes are studied using surface photovoltage studies under monochromatic light and variable intensity white light using a vibrating Kelvin probe

Inorganic Hole Conducting Layers for Perovskite-Based Solar Cells

Hybrid organic–inorganic semiconducting perovskite photovoltaic cells are usually coupled with organic hole conductors. Here, we report planar, inverse CH₃NH₃PbI_3–<i>x</i>Cl_<i>x</i>-based cells with inorganic hole conductors. Using electrodeposited NiO as hole conductor, we have achieved a power conversion efficiency of 7.3%. The maximum <i>V</i>_OC obtained was 935 mV with an average <i>V</i>_OC value being 785 mV. Preliminary results for similar cells using electrodeposited CuSCN as hole conductor resulted in devices up to 3.8% in efficiency. The ability to obtain promising cells using NiO and CuSCN expands the presently rather limited range of available hole conductors for perovskite cells

Atomic Layer Deposition of Transparent and Conducting p‑Type Cu(I) Incorporated ZnS Thin Films: Unravelling the Role of Compositional Heterogeneity on Optical and Carrier Transport Properties

Optically transparent and highly conducting p-type Cu­(I) incorporated ZnS (Cu:ZnS) films are deposited by stacking individual layers of CuS and ZnS using atomic layer deposition. The deposition chemistry and growth mechanism are studied by in situ quartz crystal microbalance. Compositional disorder in atomic scale is observed with increasing Cu incorporation in the films that results in systematic decrease in the optical transmittance in the visible spectrum. Again the conductivity also emphatically depends on the volume fraction of phase-segregated conducting covellite phase. An illustrious correlation prevailing the interplay between the optical transparency and the charge transport mechanism is established. The hole transport mechanism that indicates insulator-to-metal transition with increasing Cu incorporation in the composite is explained in terms of an inhomogeneously disordered system. Under optimized conditions, the material having moderately high optical transmission with degenerate carrier concentration lies exactly at the confluence between the metallic and insulating regime. The lowest resistivity that is obtained here (1.3 × 10^–3 Ω cm) with >90% (after reflection correction) transmission is highly comparable to the best ones that are reported in the field and probably analogous to the commercially available n-type transparent conductors