Mixed cations tin-germanium perovskite: A promising approach for enhanced solar cell applications.

Significant progress has been made over the years to improve the stability and efficiency of rapidly evolving tin-based perovskite solar cells (PSCs). One powerful approach to enhance the performance of these PSCs is through compositional engineering techniques, specifically by incorporating a mixed cation system at the A-site and B-site structure of the tin perovskite. These approaches will pave the way for unlocking the full potential of tin-based PSCs. Therefore, in this study, a theoretical investigation of mixed A-cations (FA, MA, EA, Cs) with a tin-germanium-based PSC was presented. The crystal structure distortion and optoelectronic properties were estimated. SCAPS 1-D simulations were employed to predict the photovoltaic performance of the optimized tin-germanium material using different electron transport layers (ETLs), hole transport layers (HTLs), active layer thicknesses, and cell temperatures. Our findings reveal that EA0.5Cs0.5Sn0.5Ge0.5I3 has a nearly cubic structure (t = 0.99) and a theoretical bandgap within the maximum Shockley-Queisser limit (1.34 eV). The overall cell performance is also improved by optimizing the perovskite layer thickness to 1200 nm, and it exhibits remarkable stability as the temperature increases. The short-circuit current density (Jsc) remains consistent around 33.7 mA/cm2, and the open-circuit voltage (Voc) is well-maintained above 1 V by utilizing FTO as the conductive layer, ZnO as the ETL, Cu2O as the HTL, and Au as the metal back contact. This configuration also achieves a high fill factor ranging from 87 % to 88 %, with the highest power conversion efficiency (PCE) of 31.49 % at 293 K. This research contributes to the advancement of tin-germanium perovskite materials for a wide range of optoelectronic applications.

Stabilizing high-humidity perovskite solar cells with MoS2 hybrid HTL.

The obstacle to the industrialization of perovskite solar cells (PSC) technology lies in their stability. This work rationalizes the PSC design with the employment of 2D-MoS2 as the hybrid hole transport layer (HTL). MoS2 was selected due to its unique optoelectronic and mechanical properties that could enhance hole extraction and thus boost the performance and stability of PSC devices. Five concentrations indicated MoS2 nanosheets were directly deposited onto the perovskite layer via the facile spin coating method. The electrochemical exfoliation and liquid exchange methods were demonstrated to obtain the lateral size of MoS2 nanosheets and further discussed their microscopic and spectroscopic characterizations. Remarkably, the optimum thickness and the excellent device increased the stability of the PSC, allowing it to maintain 45% of its degradation percentage ([Formula: see text]) for 120 h with high relative humidity (RH = 40-50%) in its vicinity. We observed that lithium-ion can intercalate into the layered MoS2 structure and reduce the interfacial resistance of perovskite and the HTL. Most importantly, the 2D-MoS2 mechanism's effect on enabling stable and efficient devices by reducing lithium-ion migration in the HTL is demonstrated in this work to validate the great potential of this hybrid structure in PSC applications.

Raytracing Modelling of Infrared Light Management Using Molybdenum Disulfide (MoS2) as a Back-Reflector Layer in a Silicon Heterojunction Solar Cell (SHJ).

The silicon heterojunction solar cell (SHJ) is considered the dominant state-of-the-art silicon solar cell technology due to its excellent passivation quality and high efficiency. However, SHJ's light management performance is limited by its narrow optical absorption in long-wave near-infrared (NIR) due to the front, and back tin-doped indium oxide (ITO) layer's free carrier absorption and reflection losses. Despite the light-trapping efficiency (LTE) schemes adopted by SHJ in terms of back surface texturing, the previous investigations highlighted the ITO layer as a reason for an essential long-wavelength light loss mechanism in SHJ solar cells. In this study, we propose the use of Molybdenum disulfide (MoS2) as a way of improving back-reflection in SHJ. The text presents simulations of the optical response in the backside of the SHJ applying the Monte-Carlo raytracing method with a web-based Sunsolve high-precision raytracing tool. The solar cells' electrical parameters were also resolved using the standard electrical equivalent circuit model provided by Sunsolve. The proposed structure geometry slightly improved the SHJ cell optical current density by ~0.37% (rel.), and hence efficiency (η) by about 0.4% (rel.). The SHJ cell efficiency improved by 21.68% after applying thinner back ITO of about 30 nm overlayed on ~1 nm MoS2. The efficiency improvement following the application of MoS2 is tentatively attributed to the increased NIR absorption in the silicon bulk due to the light constructive interface with the backside components, namely silver (Ag) and ITO. Study outcomes showed that improved SHJ efficiency could be further optimized by addressing front cell components, mainly front ITO and MoS2 contact engineering.

Lockdown impact on energy consumption in university building.

COVID-19 has had a significant impact on the global demand and consumption of energy. In particular, the effect of the lockdown measures due to the COVID-19 pandemic can be seen directly in the reduced energy consumption in educational buildings. Therefore, the objective of this study is to assess the impact of COVID-19 on the electricity use in university buildings. The Research Complex Building of the National University of Malaysia was selected as a case study. An energy audit analysis was conducted based on the data collection via walk-through field audits and data loggers during the normal year (2019) to establish a baseline of data. The comparison of the electricity pattern during the normal year with the lockdown period of 2020 shows that the Building Energy Index (BEI) during a pandemic decreased by approximately 11% from the BEI in the normal year. In this regard, the energy audit verified that the main factors of electricity consumption are occupant presence and energy use in buildings. Hence, on the basis of the energy audit results, three appropriate energy conservation measures (ECMs) were detected and subsequently proposed to minimise the waste of energy. Results show that the implementation of ECMs can improve the energy consumption of buildings and reduce energy consumption by 21.81% or approximately 19% from the normal year. Hence, efficient energy use in buildings in the post-pandemic period can be achieved by the implementation of all the ECMs proposed.

Carbonaceous materials and their advances as a counter electrode in dye-sensitized solar cells: challenges and prospects.

Dye-sensitized solar cells (DSSCs) serve as low-costing alternatives to silicon solar cells because of their low material and fabrication costs. Usually, they utilize Pt as the counter electrode (CE) to catalyze the iodine redox couple and to complete the electric circuit. Given that Pt is a rare and expensive metal, various carbon materials have been intensively investigated because of their low costs, high surface areas, excellent electrochemical stabilities, reasonable electrochemical activities, and high corrosion resistances. In this feature article, we provide an overview of recent studies on the electrochemical properties and photovoltaic performances of carbon-based CEs (e.g., activated carbon, nanosized carbon, carbon black, graphene, graphite, carbon nanotubes, and composite carbon). We focus on scientific challenges associated with each material and highlight recent advances achieved in overcoming these obstacles. Finally, we discuss possible future directions for this field of research aimed at obtaining highly efficient DSSCs.