Low Cost Power Research Articles

Transient starup performance of a micro horizontal axis river hydrokinetic turbine

Using the micro horizontal axis river hydrokinetic turbine to generate electricity is a low-cost power generation mode suitable for remote mountain areas. Startup performance is a key parameter related to annual power generation. Based on the numerical simulation, the influences of damping factor b, moment of inertia J, constant inflow velocity U and irregular inflow velocity (long-period and short-period inflow velocities) on the startup performance of a micro horizontal axis river hydrokinetic turbine are analyzed. Firstly, a decrease in b and J, as well as an increase in U, can reduce time required for startup. The increase of b and U cause the power coefficient Cp increase first and then decrease. The moment of inertia only affects the time required for startup, and has no impact on the Cp of the turbine in stable state. Secondly, for the long-period inflow velocity, an increase in T will result in a gradual increase in the average CP after the start-up is completed, however, the short-period has no significant effect on the mean value of each parameter. Finally, for the short-period inflow velocity, the fluctuation amplitude of hydrodynamic parameters decreases with T rising, but the fluctuation frequency increases.

A 0.8 V, 14.76 nVrms, Multiplexer-Based AFE for Wearable Devices Using 45 nm CMOS Techniques.

Wearable medical devices (WMDs) that continuously monitor health conditions enable people to stay healthy in everyday situations. A wristband is a monitoring format that can measure bioelectric signals. The main part of a wearable device is its analog front end (AFE). Wearables have issues such as low reliability, high power consumption, and large size. A conventional AFE device uses more analog-to-digital converters, amplifiers, and filters for individual electrodes. Our proposed MUX-based AFE design requires fewer components than a conventional AFE device, reducing power consumption and area. It includes a single-ended differential feedback operational transconductance amplifier (OTA) and n-pass MUX-based AFE circuits which are related to the emergence of low power, low area, and low cost AFE-integrated chips that are required for wearable biomedical applications. The proposed 6T n-pass multiplexer measures a gain of -68 dB across a frequency range of 100 kHz with a 136.5 nW power consumption and a delay of 0.07 ns. The design layout area is approximately 9.8 µm2 and uses 45 nm complementary metal oxide semiconductor (CMOS) technology. Additionally, the proposed single-ended differential OTA has an obtained input referred noise of 0.014 µVrms, and a gain of -5.5 dB, while the design layout area is about 2 µm2 and was designed with the help of the Cadence Virtuoso layout design tool.

Cotton‐Based Metal–Air Batteries without Catalysts as Low‐Cost Micropower Devices

The cotton‐based metal–air batteries without any catalyst are constructed. Especially, the continuous electrolyte flowing depends on the capillary force and the gravity from the height difference between the inlet and outlet. The performance of the cotton‐based metal–air batteries under 2 mol L−1 NaOH or NaCl solutions is compared. The Al–air battery performance in the NaOH solution is better, while the Mg–air battery performance in the NaCl solution is the best. Considering the battery performance and cost, the alkaline cotton‐based Al–air battery is investigated for the subsequent experiments. The Al–air battery performance is evaluated under the different cotton cloth makeups, NaOH concentrations, height differences between the inlet and outlet. The results show that under the conditions of the cotton makeup (20 (warp) × 60 (yarn)), 4 mol L−1 NaOH and 60 mm height difference, the battery performance is optimal, with the peak power density of 12.33 ± 0.38 mW cm−2 and limiting current density of 35.28 ± 0.73 mA cm−2. To apply the cotton‐based Al–air battery, the two‐battery stack connected in series powers 15 light‐emitting diodes. The experiments demonstrate the cotton‐based Al–air battery without catalysts owns low cost and high power output, which has great potential as a micropower device.

Spark Discharge Plasma-Enabled CO2 Conversion Sustained by a Compact, Energy-Efficient, and Low-Cost Power Supply

Spark Discharge Plasma-Enabled CO₂ Conversion Sustained by a Compact, Energy-Efficient, and Low-Cost Power Supply

Low-cost relay selection in multihop cooperative networks

A best relay selection algorithm for a cooperative multi-hop cross-layer single-input single-output (SISO) amplify-and-forward (AF) wireless relay network is analyzed in this work, with the application where exact channel state information (CSI) is known. We present algorithmic strategies to simplify a multi-hop parallel SISO relay network into a series multi-hop network by finding the best path having the maximum received signal-to-noise ratio (SNR). The best relay selection by using dynamic programming search entails high computations and large memory requirements, as well as involves the full CSI information, making this approach impractical for large-scale networks. The goal of the proposed low-cost near-optimal routing strategy in this work is to provide close to optimal performance with much less complexity compared to traditional routing. Next, we also propose a low-cost power allocation to further improve system performance over traditional power allocation found in the literature. Computer simulations show excellent performance improvement of our proposed methods in terms of bit error rate (BER) as well as outage probability over the traditional relaying and power allocation algorithms.

LoRa Backscatter Communications: Temporal, Spectral, and Error Performance Analysis

LB communication systems can be considered as a potential candidate for ultra LPWAN because of their low cost and low power consumption. In this paper, we comprehensively analyze LB modulation from various aspects, i.e., temporal, spectral, and error performance characteristics. First, we propose a signal model for LB signals that accounts for the limited number of loads in the tag. Then, we investigate the spectral properties of LB signals, obtaining a closed-form expression for the power spectrum. Finally, we derived the SER of LB with two decoders, i.e., the ML and FFT decoders, in both AWGN and double Nakagami-m fading channels. The spectral analysis shows that out-of-band emissions for LB satisfy the ETSI regulation only when considering a relatively large number of loads. For the error performance, unlike conventional LoRa, the FFT decoder is not optimal. Nevertheless, the ML decoder can achieve a performance similar to conventional LoRa with a moderate number of loads.

Development and verification of an on-board integrated optics scheme for a 50G/10G combo PON system

We propose an on-board integrated optics (OBO) scheme within a 50G/10G combo passive optical network (PON) system, for the first time to our best knowledge, which can achieve high port density, low cost, and low power consumption required by the 50G PON system. We provide an OBO scheme that integrates record-high power distributed feedback (DFB) lasers, low insertion loss silicon modulators, a planar lightwave circuit wavelength-division multiplexer, and avalanche photodiodes on a single board, which can solve key issues faced by the demand of coexistence and smooth evolution from 10G to 50G PON for global access network operators. In this system, the slope efficiency of the lasers has been optimized at high temperatures, allowing the output power of the lasers to achieve a record-breaking 23.5 dBm at 1577 and 1342 nm, while reducing cooling power consumption to realize low carbon emission in access networks. We developed a low-loss broadband silicon modulator to meet the large power budget and high data rate requirements of 50G PON by optimizing doping parameters and constructing electrodes that match the driver. This silicon modulator has a 6.6 dB insertion loss and an electro-optic bandwidth of more than 38 GHz, making it the ideal silicon modulator for 50G PON systems. In addition, we verify the end-to-end performance, including receiver sensitivity in the upstream direction and the dispersion penalty in the downstream direction. This suggests that the OBO scheme can satisfy the criteria of the 50G PON system according to the ITU-T G.9804 standard series.

High efficiency dye-sensitized solar cells with a novel two dimensional Cd-V-LDH photoanode

The present study demonstrates a novel photoanode layer double hydroxide (LDH) for dye-sensitized solar cells (DSSCs). The search for a photoanode (PA) with low cost and high power conversion efficiency (PCE) has become one of the most significant challenges facing researchers. LDH has proven successful as a photocatalyst in various fields. In this paper, a novel Cd-V-LDH with a molar ratio of Cd:V = 1:1 was synthesized by the coprecipitation method and used as a novel PA in DSSCS. X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FTIR), Nitrogen sorption analysis, UV–Vis absorption spectrum, Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to examine the produced Cd-V-LDH. Cd-V-LDH as PA, Eosin Y (EY) as a photosensitizer, LiI-I2 as a liquid electrolyte, and g-C3N4 (GN) as a photocathode (PC) are the component of DSSCs. The series cells of DSSCs were assembled and the available variables have been studied to achieve the best performance under normal conditions. These variables, e.g., concentration and pH of EY, active area of PA, and different types of PC, e.g., graphene oxide (GO), commercial carbon (CC), and (GN). The open circuit voltage (VOC) and short circuit current density (JSC) for the Cd-V-LDH/EY/LiI-I2/GN system were observed to be 705 mV and 12.40 mA/cm2, and has a PCE of 5.4% comparable to Cd-V-LDH/EY/LiI-I2/GO and Cd-V-LDH/EY/LiI-I2/CC, which have PCEs of 4.9% and 3.8%, respectively, in the identical testing conditions.

Air pollution forecasting based on wireless communications: review.

The development of contemporary artificial intelligence (AI) methods such as artificial neural networks (ANNs) has given researchers around the world new opportunities to address climate change and air quality issues. The small size, low cost, and low power consumption of sensors can facilitate obtaining the values of polluting gases in the atmosphere. However, several problems with using air pollution technique relate to various effects such as sensing accuracy, sensor drifts, and sluggish reactions to changes in pollution levels. Recently, machine learning has made it feasible to build a more intelligent, context-aware system that can anticipate events and monitor present conditions. This paper focuses on the use of environment sensors for detecting air pollution based on several types of wireless protocols, including Wi-Fi, Bluetooth, ZigBee, LoRa, Global Positioning System (GPS), and 4G/5G. Furthermore, it classifies previous published articles on the topic according to the wireless protocol and compared in terms of several performance metrics such as the adopted air pollution sensors, hardware platform, adopted algorithm, power consumption or power savings, and sensing accuracy. In addition, this work highlights the challenges and limitations facing drones during their mission for detecting air pollution. As a result, we suggest to build and implement at base station an intelligent system based on backpropagation (BP) neural networks, which provides flexibility to track and predict the true values of polluting gases in the atmosphere to overcome the above problems. Finally, this work addresses the advantages of using drones in the air pollution field.

An Improved Constant Current Control Scheme for Multimode PSR Flyback Converter

For low cost and wide power range, the constant current (CC) control scheme for multimode primary-side regulation (PSR) flyback converter is prevalent in low and medium power applications. Although some multimode CC control schemes have been presented to raise CC accuracy, the current deviation caused by the mode conversion and inherent propagation delay remains unsolved. An improved CC control scheme is adopted to mitigate the influence of propagation delay or mode conversion on CC accuracy, which can be added into an IC controller with no extra pin penalty. The proposed scheme is implemented in 0.18lm 5V/40V BCD process. The experimental results reveal that the deviation of the output current is within 1 0.8% under different input and load conditions.

A Low-Cost Battery-Balancing Auxiliary Power Module With Dual-Active Half Bridge Links and Coreless Transformers

Redistributive balancing brings many benefits to electric vehicles, such as increased range and more uniform cell degradation. Despite previous analyses suggesting a 17-36% extension of battery lifetime, the cost of such systems has prevented the technology from being adopted in practice. This study proposes a simplified topology for battery-balancing auxiliary power modules with reduced magnetic material to achieve cost-friendly solutions without sacrificing functionality or balancing modes. The proposed system consists of a dual-active half bridge, halving the number of switches needed compared with the conventional dual-active bridge. In addition, the transformer core material is removed and a coreless transformer is used to provide isolation and energy transfer. Both changes reduce the cost of redistributive balancing. The topological modeling differs from cored transformer circuits as the coupling of the coreless transformer is weaker. The coupling coefficient is now used in an updated model that includes transformer currents and output powers. These, along with the balancing modes, are analyzed then experimentally verified. The proposed models can guide the selection of MOSFETs and the design of the coreless transformer. An analytic projection shows up to a 22% cost reduction compared with similar topologies.

(Invited) The SOFC Program at the DOE’s Office of Fossil Energy and Carbon Management (FECM) and National Energy Technology Laboratory (NETL)

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy (FE) and administered by the FE’s National Energy Technology Laboratory (NETL) is currently developing low-cost SOFC power generation systems. SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation. In addition, there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several projects on various aspects of high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants.

(Best Student Presentation) Extending the NaCl-AlCl3 Phase Diagram to Enable Low-Cost, Long-Duration Na-Al Batteries for the Grid

Achieving deep grid decarbonization via intermittent renewable power sources requires extensive grid-scale energy storage technologies to deliver stable power during periods of low generation. Doing so at scale and at low cost further adds to this challenge, as current solutions generally rely on geographically limited solutions such as pumped hydro storage, or costly battery chemistries focusing primarily on Li-ion technologies. As an alternative, battery systems based on lower cost materials such as sodium offer an attractive alternative for low-cost, scalable, and non-geographically limited electrochemical energy storage.This work combines an abundant and inexpensive molten sodium metal anode with a cost-effective aluminum cathode to provide a proof-of-concept alternative for grid-scale energy storage. Building on prior work utilizing the high reversibility of the neutral sodium chloroaluminate (NaAlCl4) molten salt electrolyte commonly used for classic molten sodium batteries, this work demonstrates greater capacity utilization of the NaCl-AlCl3 binary system by ‘overcharging’ this Na-Al battery to form an acidic chloroaluminate catholyte, NaAl2Cl7. Leveraging the reaction between NaAlCl4 and NaAl2Cl7 in conjunction with that between Al/NaCl and NaAlCl4 advantageously utilizes the majority of Na available in the cathode for capacity, in addition to providing a higher discharge voltage (~ 2 V compared to ~ 1.6 V for the NaAlCl4 reaction), thereby adding ~ 119 Wh kg-1 additional specific energy, on top of the 493 Wh kg-1 theoretical specific energy of the neutral Na-Al battery reaction between Al/NaCl and NaAlCl4.Fundamental aspects of the acidic chloroaluminate reaction are investigated, showing that cells using only the acidic reaction are able to cycle for hundreds of cycles. The acidic reaction between NaAlCl4 and NaAl2Cl7 occurs via a solution-phase reaction, unlike the two-phase neutral reaction between NaCl/Al and NaAlCl4, and we confirm via Raman and NMR spectroscopies that complete conversion to NaAl2Cl7 occurs at end of charge. Na-Al batteries utilizing both reactions demonstrate high areal capacity (~ 46 mAh cm-2) and excellent reversibility. Enabled by the rapid mass transfer and solid-liquid reaction mechanism of the chloroaluminate catholyte, a higher areal capacity cell with ~ 132 mAh cm-2 is demonstrated, allowing a discharge duration of 28.2 h, implying that this Na-Al battery chemistry may be suitable for long-duration energy storage for grid applications. Finally, the raw active materials cost of this battery is estimated to be only ~ $7 kWh-1, which is promising for enabling low-cost renewable power utilization for the grid. Figure 1

Low-Cost Maximum Power Point Tracking Strategy and Protection Circuit Applied to an Ayanz Wind Turbine with Screw Blades

This paper provides three different research contributions applied to a Wind Turbine patented in 1606 by the inventor Jerónimo de Ayanz y Beaumont. The windmill under study is the Ayanz Wind Turbine with screw blades. The first contribution consists of an experimental characterization of the Ayanz Wind Turbine, incorporating the enclosure proposed at the patent and showing that the efficiency of the wind turbine is increased between 70% and 90% due to the enclosure being employed. As not many details about the shape of the screw blades are provided at the patent, in this article the nowadays well-studied and commercially available Archimedes Spiral Wind Turbine blade is utilized. It has been observed that by using an enclosure with a cylindrical shape, not only the efficiency of the wind turbine is increased, but the visual impact is reduced as seeing the blades rotating is avoided, which is a very important fact for many potential individual users of this wind turbine. In addition, it also enables the use of a protective mesh for birds, almost totally reducing the probability of bird deaths. The second contribution consists in a simple and low-cost Maximum Power Point Tracking (MPPT) strategy for the wind turbine, which only uses an AC three-phase impedance to capture the maximum energy from the wind, enabling to eliminate the DC-DC converter and microprocessor employed typically for this purpose. Due to this, the cost, complexity, failure rate, and power losses of the electronic power circuit are reduced which is very welcomed for small-scale wind turbines. Finally, the last contribution is a protection electronic circuit that fulfills several objectives: to brake the wind turbine under high winds and to disconnect and protect it when over-currents occur and when the voltage range of the batteries connected to the wind turbine is outside their safety range.

LoRaWAPS: A Wide-Area Positioning System Based on LoRa Mesh

The positioning task of the Internet of Things (IoT) for outdoor environments requires that the node devices meet the requirements of low power consumption, long endurance, and low cost and that the positioning system can achieve high-precision positioning and wide-area coverage. Considering that traditional IoT positioning technology cannot balance the cost, energy consumption, and positioning performance well, a Wide-Area Positioning System Based on Long Range Mesh (LoRaWAPS), which is a low-cost and low-power outdoor positioning system with multi-anchor wireless mesh networking and multi-dimensional data fusion, is designed in this paper. To meet the need for a positioning system, a low-power consumption and high-reliability LoRa Mesh protocol is proposed. Aiming at the problem that the accuracy of LoRa ranging is easily affected by the non-line-of-sight (NLOS) path propagation of signals, a distance estimation algorithm based on the fusion of time of flight (TOF) and received signal strength indicator (RSSI) multi-sampling data is proposed. Furthermore, a position estimation algorithm is designed to minimize the posteriori RSSI error for multi-anchor cooperative estimation scenarios. Furthermore, the prototype of LoRaWAPS is built and tested in the campus environment. The experimental results show that the proposed system can provide reliable location service with low power and low cost.

Optimization of control strategy for air-cooled PEMFC based on in-situ observation of internal reaction state

Air-cooled proton exchange membrane fuel cell (PEMFC) is a promising electrochemical device in fields of unmanned aerial and light-duty ground vehicles， with the virtues of simple system, low parasitic power and low cost. However, the significantly uneven distribution of internal reaction state of air-cooled PEMFC greatly limits the output performance and stability of the cells. In this study, a PCB test board for the in-situ observation of cell temperature and current density is designed and applied in fuel cells. The result shows that when the average current density is 500 mA/cm2，the difference of temperature and current density reach 20 °C and 400 mA/cm2, respectively. For the optimization of uniformity of reaction state, the effects of hydrogen pulsing interval, hydrogen supply mode, fan configuration and air inlet speed are experimentally explored. Based on the observed results of the PCB test board, optimization proposals of control strategy for air-cooled PEMFC are given: 1) A 30-s pulsing interval of hydrogen is preferred due to its little changes on current density distribution while significant increasement of hydrogen utilization rate. 2) The proposed bidirectional hydrogen flow improves the reaction uniformity, and reduces the fluctuation of current density during hydrogen pulsing discharge; 3) Compared to two paralleled fans, employing a single fan helps to improve the temperature uniformity, with the standard deviation of temperature from 8.9 °C to 6.7 °C; 4) Medium velocity of air inlet speed is preferred due to poor temperature uniformity at low velocity, and low water content at high velocity.

Aggregation Dispatch and Control Strategies for Multi-Type Loads in Industrial Parks

With the continuous expansion of renewable energy construction, the power system requires a larger-scale flexible dispatchable and controllable resource for power balance. Fully tapping into the power regulation capability of multi-type loads in industrial parks, making them a low-cost flexible dispatchable and controllable resource, is an effective approach to establish power regulation capability at scale in the new power system. However, the control characteristics of multi-type loads in industrial parks vary greatly, and their control delay characteristics, response speed, and sustainable response time are all different. Traditional dispatch and control methods cannot achieve precise control of the massive and multi-type loads in industrial parks. Therefore, this paper establishes unified models for the control characteristics of multi-type loads in industrial parks, quantitatively characterizes their control delay characteristics, start–stop characteristics, and control response speed. Based on this, the aggregated dispatch and control model and dispatch and control strategy for multi-type loads in industrial parks are developed, which provide a predictive control rate for individual loads considering the delay and segmented response characteristics to achieve precise aggregation control of multi-type loads in industrial parks. Simulation results show that the aggregated dispatch and control model and its aggregated dispatch and control strategy achieve precise control of multi-type loads in industrial parks. Flexible dispatchable and controllable loads can provide low-cost power regulation capability for the new power system.

Single-carrier 800-Gb/s self-homodyne coherent transmission of DP-16QAM, DP-32QAM, and DP-64QAM with uncooled DFB laser.

Self-homodyne detection (SHD) is a promising approach to realize high-capacity short-reach optical transmission systems with low cost and low power consumption. We experimentally demonstrate single-carrier net 800-Gb/s SHD transmission with low-cost ∼MHz linewidth distributed feedback (DFB) laser over 2 km, 10 km, 25 km, and 40 km single-mode fiber (SMF) using three different quadrature amplitude modulation (QAM) formats, including 80-Gbaud dual-polarization (DP) 64QAM, 100-Gbaud DP-32QAM, and 120-Gbaud DP-16QAM. Among them, net 800-Gb/s DP-64QAM SHD transmission over 25 km SMF using an uncooled DFB laser with a linewidth of 2.6 MHz is experimentally verified. The detailed experimental performance evaluation of net 800Gb/s SHD system is performed, in which various configurations are considered, such as different laser linewidths, three QAM formats, and different transmission distances. DFB lasers with linewidths of 1 MHz and 2.6 MHz lead to negligible penalty when compared to the same SHD system but using an external cavity laser (ECL) with a linewidth of 26kHz in back-to-back (BTB) case. 80-Gbaud DP-64QAM obtains the highest optical signal-to-noise ratio (OSNR) requirement and the highest bit-error rate (BER) floor but the best tolerance of chromatic dispersion (CD). 120-Gbaud DP-16QAM achieves the lowest OSNR requirement and the lowest BER floor but the worst tolerance of CD. The detailed experimental investigation is conducive to promote the practical application of SHD in different short-reach scenarios.

An IoT-based handheld environmental and air quality monitoring station

Weather and air quality play an important role in determining environmental pollution. Fluctuation of these parameters not only causes environmental pollution but also causes severe injuries to human health. With the emergence of the Internet of Things (IoT), sensor-based weather devices with easy observation facilities started to develop. In this regard, this study focused on developing an IoT-based portable weather monitoring gadget that can measure weather and air parameters which are more often required in our day-to-day life. The proposed system is capable to measure temperature, pressure, humidity, altitude, PM2.5, PM10 level, VOC, and CO level. It consists of a portable display and a mobile app with a thing speak cloud platform. Further, the system has a Wi-Fi and GSM connection to communicate data. A mobile application was developed to monitor the readings in real-time which are stored in the cloud platform. The developed hardware was carefully calibrated in the national meteorological department to make sure our system is practically usable. Compared to existing models, our prototype is very handholdable, easily installable which does not require trained technicians, and is easily maintainable. Also, it is possible to access the data from anywhere in the world through Wi-Fi connectivity, and possible to make data visualization and analysis. On the other hand, it is very difficult to find a single, portable size, and low-cost device to collect all these parameters together. Nonetheless, our prototype has the potential of connecting with multiple similar devices to create a larger IoT network grid. Overall, our proposed product has a combination of weather and air quality parameters in a portable and handholdable size with low-cost and low power consumption which other devices do not have according to the latest literature.

Solvent engineering of SnO2 electron transport layer for high-performance perovskite solar cells

Perovskite solar cells (PSCs) show great potential as industrial photovoltaic devices due to their low fabrication cost and high power conversion efficiency. Owing to high electron conductivity and good energy level matching with perovskites, SnO2 is widely used as electron transport layers (ETLs) for PSCs. However, the agglomeration of SnO2 nanoparticles makes them have poor contact with the glass substrate and it is easy to produce defects on the film surface. Herein, acetonitrile (ACN) is used to optimize the conventional solvent of commercial SnO2 colloid to solve these problems. The addition of ACN in solvent resulted in better-performing SnO2 ETLs, thus eliminating the need for long-time ultraviolet ozone (UV-ozone) treatment of the glass substrate, which undoubtedly greatly simplified the fabrication process. The subsequent vacuum treatment of SnO2 films before annealing further improves morphology of the ETLs film and performance of the overall device. Finally, the best devices after the above solvent engineering treatment achieved an efficiency of 22.28%, increased by 16% with respect to the control device fabricated by conventional method. In addition, the long-term stability of devices was also apparently improved. This solvent engineering strategy provides a simple route to prepare high-quality SnO2 ETL for high-performance PSCs.