In recent years, there has been an unprecedented rise in the performance of metal halide perovskite solar cells. The lead-free perovskite solar cells (PSCs) have drawn much research interest due to the P b toxicity of the lead halide perovskite. CH 3 NH 3 SnI 3 is a viable alternative to CH 3 NH 3 PbX 3. In this work, we designed a tin-based perovskite simulated model with the novel architecture of (TCO)/buffer (TiO 2)/absorber (Perovskite)/hole transport material (HTM) and analyzed using the solar cell capacitance simulator (SCAPS-1D), which is well adapted to study the photovoltaic architectures. In the paper, we studied the influences of perovskite thickness and the doping concentration on the solar cell performance through theoretical analysis and device simulation. The results are indicating that the lead-free CH 3 NH 3 SnI 3 is having the great potential to be an absorber layer with suitable inorganic hole transport materials like CuI (PCE: 23.25%), Cu 2 O (PCE: 19.17%), organic hole transport materials like spiro-OMETAD (PCE: 23.76%) and PTAA (PCE: 23.74%) to achieve high efficiency. This simulation model will become a good guide for the fabrication of high efficiency tin-based perovskite solar. The results show that the lead-free CH 3 NH 3 SnI 3 is a potential environmentally friendly solar cells with high efficiency.

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Numerical simulation has been used to investigate the effect of different buffer layer components on the performance of CuInGaSe 2 solar cells with SCAPS-1D software. The main photovoltaic parameters of simulated devices: open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and conversion efficiency (η), are analysed as a function of thickness and temperature in the different buffer layers used. According to numerical simulation the highest conversion efficiency (23%) of CIGS solar cell is reached for the CdS buffer layer. This result is validated by experimental results (20%). At 300 K, when the thickness of the buffer layer (CdS, ZnS, ZnSe, InSe 2 ) increases from 100 nm to 500 nm, with the other parameters maintained constant, the efficiency decreases. When the temperature increases from 300 K to 400 K, with the other parameters maintained constant, both open circuit voltage and conversion efficiency also decrease. The effect of dual buffer layers of ZnS/CdS has also been analysed and his efficiency increases of 3% than a single buffer CdS.

In this study, the authors address the problem of combining hierarchical and flat techniques to construct and maintain nodes' connectivity as well as links' symmetry (bidirectionality) in a wireless sensor network (WSN) comprising static nodes. They propose a localised and asynchronous self-stabilising hybrid message passing a solution that seamlessly merges three well known connectivity control techniques for such ad hoc networks, namely k-hop clustering (k ≥ 1), power control (transmission range adjustment) and sleep/wake scheduling. Their stigmergy-based strategy (i.e. inspired from ants' pheromone-based communication, division of labour and swarming behaviours) allows a WSN to simultaneously cope with issues such as scalability, fault tolerance, transmission range minimisation, energy hole problem (i.e. premature node deaths in the vicinity of the sink), channel overhearing and signalisation reduction. To the best of their knowledge, such a solution does not exist in the literature. The few self-stabilising hybrid connectivity control protocols currently proposed use only two of the above-mentioned techniques. The authors formally prove the correctness of their scheme and its self-stabilisation property under an unfair distributed daemon. Simulation results show that the proposed scheme has a low average convergence time, is energy efficient and can prolong network lifetime.