Hybrid organic–inorganic semiconducting perovskite photovoltaic cells are usually coupled with organic hole conductors. Here, we report planar, inverse CH3NH3PbI3–x Cl x -based cells with inorganic ...hole conductors. Using electrodeposited NiO as hole conductor, we have achieved a power conversion efficiency of 7.3%. The maximum V OC obtained was 935 mV with an average V 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 (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.
Though perovskite solar cells (PSC) have reached high efficiency comparable to its counterparts, it is still striving towards finding a strong hold in terms of long-term stability. Several approaches ...have been made to prevent the degradation of PSC. Here, we present low-temperature ALD deposited Al2O3 as an effective encapsulant for PSC. The encapsulated devices improve with PCE reaching up to 19.4% post 300 cycles of Al2O3 deposition. In-situ QCM and FTIR measurements reveal that trimethylaluminum gets trapped inside the spiro-OMeTAD layer and is available for the subsequent dosage of H2O during nucleation regime. Here we unveil the fact that the ALD grown Al2O3 is not only surface limited, but the material penetrates the spiro-OMeTAD and enhances the hole transport property, improving the overall performance of encapsulated cells. Intermittent measurements indicate that encapsulated cells are stable, retaining 84% of its initial efficiency by the end of 300 days. Subsequently we elucidate that the device measurements under continuous illumination and with different bias conditions and atmosphere show that the ALD grown encapsulation prevents ingress of moisture and oxygen into the cells maintaining their stability.
•ALD-Al2O3 encapsulated PSC retained 84% of initial efficiency by the end of 300 days of intermittent measurement in ambient.•In-situ QCM showed non-linearity in mass change until a complete surface coverage after which it reaches the linear growth regime.•In-situ FTIR revealed continuous addition of Al–CH3 on the bulk of spiro-OMeTAD upon TMA exposure during the nucleation regime.
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.
In this report we have discussed the need of conformal deposition of the low bandgap materials as absorber in solid-state bulk heterojunction devices. We demonstrated ALD grown Sb 2 S 3 and TiS x ...thin films for photovoltaic applications. The deposition mechanism was studied in depth using in-situ quartz crystal microbalance (QCM). Need of modified reactor configuration for the uniform deposition of the material throughout the depth of the mesoporous host was discussed with elaborated comparative results for various absorber material device configurations.
Radio‐frequency magnetron sputtering is demonstrated as an effective tool to deposit highly crystalline thin zinc oxide (ZnO) layer directly on perovskite absorber as an electron transport layer ...(ETL). As an absorber, formamidinium lead tribromide (FAPbBr
3
) is fabricated through a modified single‐step solution process using hydrogen bromide (HBr) as an additive resulting in complete surface coverage and highly crystalline material. A planar p–i–n device architecture with spin‐coated poly‐(3,4‐ethylenedioxythiophene):poly‐styrenesulfonic acid (PEDOT:PSS) as hole transport material (HTM) and sputtered ZnO as ETL results in a short circuit current density of 9.5 mA cm
−2
and an open circuit potential of 1.19 V. Numerical simulations are performed to validate the underlying loss mechanisms. The use of phenyl C
60
butyric acid methyl ester (PCBM) interface layer between FAPbBr
3
and sputter‐coated ZnO offers shielding from potential plasma‐related interface damage. The modified interface results in a better device efficiency of 8.3% with an open circuit potential of 1.35 V. Such devices offer better stability under continuous illumination under ambient conditions in comparison with the conventional organic ETL (PCBM)‐based devices.
Radio-frequency magnetron sputtering is demonstrated as an effective tool to deposit highly crystalline thin zinc oxide (ZnO) layer directly on perovskite absorber as an electron transport layer ...(ETL). As an absorber, formamidinium lead tribromide (FAPbBr sub(3)) is fabricated through a modified single-step solution process using hydrogen bromide (HBr) as an additive resulting in complete surface coverage and highly crystalline material. A planar p-i-n device architecture with spin-coated poly-(3,4-ethylenedioxythiophene):poly-styrenesulfonic acid (PEDOT:PSS) as hole transport material (HTM) and sputtered ZnO as ETL results in a short circuit current density of 9.5 mA cm super(-2) and an open circuit potential of 1.19 V. Numerical simulations are performed to validate the underlying loss mechanisms. The use of phenyl C sub(60) butyric acid methyl ester (PCBM) interface layer between FAPbBr sub(3) and sputter-coated ZnO offers shielding from potential plasma-related interface damage. The modified interface results in a better device efficiency of 8.3% with an open circuit potential of 1.35 V. Such devices offer better stability under continuous illumination under ambient conditions in comparison with the conventional organic ETL (PCBM)-based devices. Radio-frequency sputtering is used as an effective tool to deposit inorganic electron transport layer (ETL) directly on top of perovskite absorber. Here, FAPbBr sub(3)-based planar p-i-n devices are fabricated with sputtered zinc oxide (ZnO) as an ETL; resulting in devices with efficiencies close to 6%. Further interfacial modifications result in 8.3% of efficient devices with better device stability.
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