Search

CuCl2 solutions of various molarities were used to treat CdSe thin films produced by RF magnetron sputtering. In-depth investigation on the impacts of this treatment on CdSe thin films were studied. The structural investigation revealed that all as-grown films exhibited the hexagonal phase peak at the (101) plane. The crystalline and grain sizes increased with CuCl2 treatment, reaching 114 nm for 0.1 M CuCl2-treated CdSe thin film. A granule-like morphology was seen on the treated films. Opto-electric study revealed that CuCl2 treatment improved CdSe film properties and tailored structural restrictions. The 0.30 M CuCl2 treatment was shown to be an important process parameter for the CdSe thin films, indicating its potential as a photovoltaic material.

We measure the minority carrier lifetime of perovskite films by differential microwave photoconductivity decay (μ-PCD). Clear decay curves can be detected from bare and laminated methylammonium lead iodide (MAPbI3) films by the differential μ-PCD. The degradation of the bare and laminated MAPbI3 films under air exposure at room temperature is clearly observed as the continuous change of the decay curves. The differential μ-PCD can thus be a quick and non-destructive method for the characterization of the electrical quality of perovskite films and modules.

We have investigated the use of n-type amorphous silicon (n-a-Si) films as the electron transport layers (ETL) in perovskite (PVK) solar cells, aiming at the application to PVK/Si tandem solar cells. The use of n-a-Si as the ETL in MAPbI3 PVK solar cells was attempted, and the power conversion efficiency (PCE) of fluorine-doped tin oxide- (FTO-) based solar cells was improved due to an improvement in coverage on FTO with thicker n-a-Si, but the external quantum efficiency in the short wavelength region was decreased due to parasitic absorption of n-a-Si. The use of indium tin oxide with a flat surface resulted in a PCE of 1.25% for the solar cells with 10 nm-thick n-a-Si. This work indicates that n-a-Si is a potential ETL candidate for PVK solar cells and provides strategic guidance for the future vacuum-integrated process of PVK/Si heterojunction tandem solar cells, which can be feasible for efficient mass production.

The fabrication of high-efficiency solution-processable perovskite solar cells has been achieved using mesostructured films and compact titanium dioxide (TiO2) layers in a process that involves high temperatures and cost. Here, we present an efficient approach for fabricating chemical-bath-deposited, low-temperature, and low-cost amorphous compact TiO x -based planar heterojunction perovskite solar cells by one-step and two-step coatings of the perovskite layer. We also investigate the effect of the number of perovskite coating steps on the compact TiO x layer. The grazing incidence wide-angle X-ray scattering technique is used to clarify the relationship between morphology, crystallinity, and photovoltaic properties of the resulting devices. Analysis of the films revealed that one-step spin-coating of perovskite exhibited an enhancement of film quality and crystallization that correlates to photovoltaic performance 1.5 times higher than that of a two-step-coated device. Our findings show that the resulting morphology, crystallinity, and device performances are strongly dependent on the number of coating steps of the perovskite thin layer on the compact TiO x layer. This result is useful knowledge for the low-cost production of planar perovskite solar cells.

Cesium iodide (CsI) is attracting attention as a substitute for organic materials such as CH3NH3I. In this work, we fabricated sequential-vacuum-deposited planar heterojunction (PHJ) cesium lead iodide (CsPbI3) perovskite solar cells with enhanced efficiencies by varying the annealing time (0.5, 1, 5, and 10 min). The effect of performance enhancement was investigated as a function of varying annealing time at 350 °C employing a hot plate. The best-performing device was obtained with an annealing time of 1 min, delivered photocurrent density (J SC) of 12.06 mA/cm2, voltage (V OC) of 0.71 V, and fill factor (FF) of 0.67, leading to a power conversion efficiency (PCE) of 5.71% at standard AM 1.5G solar illumination.

Organic–inorganic hybrid perovskite materials have recently emerged as a promising cost- and energy-efficient light absorber material for photovoltaic applications. Unfortunately, perovskite solar cells have a problem with decreasing power conversion efficiency owing to their degradation in air. To clarify the cause of the degradation of perovskite solar cells, we exposed deposited CH3NH3PbI3 and HC(NH2)2PbI3 films to an O2 or (H2O+N2) atmosphere condition. Analysis of these films revealed that a large energy band gap was observed as a result of the influence of the H2O molecule in CH3NH3PbI3 and HC(NH2)2PbI3. Under the (H2O+N2) atmosphere condition, the existence of CH3NH3I and HC(NH2)2I molecules was found to affect the morphology and as well as the crystalline diffraction peak. The resultant perovskite crystalline structure was degraded by H2O molecules under the air exposure condition.

Hybrid organic/inorganic perovskites such as methylammonium lead iodide (CH3NH3PbI3) are potential candidates for thin-film photovoltaics because of their excellent cost- and energy-efficient light absorption. In this work, we have prepared CH3NH3PbI3 nanoparticles (NPs) on the TiO x /ITO glass substrates by a simple spin-coating method to control the size and shape of NPs. The effect of varying the weight percentage (wt %) of ionic liquid (IL) has also been investigated. Analysis of the films revealed spherical NP morphology in the presence of 1, 3, and 7 wt % IL with respective diameters of 540, 350, and 600 nm. Conversely, 10 wt % IL resulted in irregular aggregation of NP blocks. The power conversion efficiency (PCE) changed upon varying the NP size, shape, and morphology. The optimization of the concentration with 3 wt % IL yielded NPs with the most uniform shape, size, and morphology and, consequently, the maximum PCE.