Since the conversion efficiency of silicon (Si)-based solar cells stagnates at 26.7% in the literature, extensive research and development activities are carried out on perovskite silicon-based tandem solar cells. However, the presence of lead (Pb) and the instability of perovskite prevent their large-scale implementation in the photovoltaic industry. Therefore, it is important to replace the hazardous material (Pb) in perovskite top cells to design non-toxic perovskite–silicon tandem solar cells. The current work yields much-needed studies to develop a non-toxic perovskite–silicon-based tandem solar cell. For the first time, methylammonium tin mixed halide (MASnI3–x Br x )-based materials are comprehensively investigated and optimized with respect to different halide compositions, absorber layer thickness, and bulk defect density in standalone configurations, followed by the development of a lead-free MASnI2Br1–Si-based tandem solar cell. The transfer matrix method and current matching techniques are used to design the two-terminal monolithic tandem cell, which showed a maximum conversion efficiency of 30.7% with an open circuit voltage (V OC) of 2.14 V. The results outlined in this manuscript will pave the way for the progress of highly efficient, non-toxic perovskite–silicon tandem solar cells.

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Operational Transconductance Amplifier (OTA) is an important circuit block used in the design of filter, amplifiers and oscillators for various analog-mixed circuit systems. However, design of a low-noise, high-gain OTA with low-power consumption is a challenging task in CMOS technology owing to high-power requirements of OTA for emulating high gain. This paper represents the design of gate-driven quasi-floating bulk recycling folded cascode (GDQFB RFC) OTA which has been shown to provide low-noise operation, emulates high gain and draws very less power. The design utilizes the gate-driven quasi-floating bulk (GDQFB) technique on a recycling folded cascode structure, which enhances the transconductance of OTA and improves its performance. All the post-layout simulation results have been obtained in 0.18-[Formula: see text]m CMOS N-well technology using BSIM3V3 device models. The obtained results indicate very high gain of 100.4 dB, gain-bandwidth of 69[Formula: see text]kHz, phase margin of 51.9∘ with power consumption of 2.31[Formula: see text][Formula: see text]W from [Formula: see text][Formula: see text]V supply voltage. The input referred noise emulated by proposed OTA is 0.684, 0.21 and 0.0592[Formula: see text][Formula: see text]V/[Formula: see text]Hz @ 1[Formula: see text]Hz, 10[Formula: see text]Hz and 1[Formula: see text]kHz, respectively. The input common mode range and output voltage swing are found to be [Formula: see text] to 0.669[Formula: see text]V and [Formula: see text] to 0.610[Formula: see text]V, respectively. Corner simulations and Monte Carlo analysis have been performed to verify the robustness of the proposed OTA. The proposed OTA can be used in design of filters and amplifiers for bio-instruments, sensor applications, neural recording applications and human implants etc.

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Cryptocurrency mining and blockchain technology using renewable energy as the main electricity source has gained attention for sustainable development in financial areas. However, very few studies have been reported concerning the power usage of cryptocurrencies using renewable energy. In this article, we report the effect of overclocking and undervolting on power usage and the hash rate for mining dogecoin with solar energy as renewable energy. The mining rig used in this work consists of different graphics processing units (GPUs) and non-LHR (lite hash rate) cards. The UnMineable software has been used for mining dogecoin as well as for wallet integration. The results indicate that mining dogecoin with solar energy as renewable energy consumes 2000 Watts power with overclocking and 1700 Watts power with undervolting technique. This work implicates the potential future of crypto-mining with renewable energy and the hardware configuration associated with it, which is expected to reduce e-waste and improve sustainable development. To reduce the e-waste and high electricity consumption, we have introduced two important techniques named GPU optimization and use of renewable energy for mining, which helps the miners to reduce the e-waste and electricity consumption significantly at the same time getting most out of the GPU by not having any impact on the environment.