Indoor Light Energy Harvesting Research Articles

Performance of Hydride Vapor Phase Epitaxy‐Grown GaInP Photovoltaics with Double‐Sided Al‐Containing Passivation Layers Under Air Mass 1.5 Global Solar Irradiation and Low‐Intensity Indoor Light Irradiation

High‐performance III–V photovoltaic devices have the potential for various applications; however, their high production cost represents a challenge for market expansion. Hydride vapor phase epitaxy (HVPE) is a fabrication technology that can reduce the epitaxial growth cost of III–V compound semiconductors. This study demonstrates the performances of HVPE‐grown GaInP photovoltaic devices for solar and indoor photovoltaic applications. Herein, HVPE‐grown GaInP photovoltaic devices with AlInP frontside and AlGaInP backside passivation layers are fabricated for the first time. The developed GaInP photovoltaic device measured under air mass 1.5 global solar spectrum illumination achieves an independently certified power conversion efficiency of 17.3%, which is a new record efficiency among HVPE‐grown GaInP single‐junction solar cells. Furthermore, the GaInP photovoltaic device grown using HVPE exhibits a high power conversion efficiency (34.7–37.1%) under an illumination of 500–2000 lux, respectively, emitted by a white light‐emitting diode. These results demonstrate that HVPE‐grown GaInP photovoltaic devices can be used in low‐intensity indoor light energy harvesting systems.

Indoor light energy harvesting technique to energize a heat sensor using polycrystalline solar panel

This paper presents the effect of using different illumination types between the polycrystalline solar panel and the light sources on energy harvesting performance for indoor low-power applications such as heat sensors. The main advantage of indoor energy harvesting is it makes good use of ambient energy from the environment and converts it directly to electricity for small power devices. In this paper, the maximum power of polycrystalline solar panels for four different light illuminations has been investigated under different distances of light sources from the polycrystalline solar panel. Implementation and test results of the effect of varying the distance and the power produced for different light illuminations are presented which highlights the practical issues and limitations of the system.

Canatu and Webasto win Plug and Play Global Innovation Award at Startup Autobahn EXPO2023 / Heliatek joins European Solar PV Industry Alliance (ESIA) / Linxens: Revolutionising connected healthcare through printed electronics / Dracula Technologies sets new standards in indoor light energy harvesting

Canatu and Webasto win Plug and Play Global Innovation Award at Startup Autobahn EXPO2023 / Heliatek joins European Solar PV Industry Alliance (ESIA) / Linxens: Revolutionising connected healthcare through printed electronics / Dracula Technologies sets new standards in indoor light energy harvesting

Characteristics of Dye-Sensitized Solar Cell under PWM Illumination: Toward Indoor Light-Energy Harvesting in the Solid-State Lighting Era

The dye-sensitized solar cell (DSSC) has been on the market as a permanent power source for indoor IoT edge devices. In recent years, indoor illumination technology has been experiencing a drastic transition from incandescent and fluorescent lamps toward solid-state lighting devices with light-emitting diodes (LEDs). In addition to the high power efficiency, a virtue of LEDs is their prompt response, which enables precise change of the illumination level using pulse-width modulation (PWM) of the current source, and thus PWM illumination is commonly installed in society. The light intensity change from off to on states of an LED under PWM driving is literally infinity, which causes the lighting to flicker. The lighting flicker induces not only an optical illusion but also biological effects, including serious health problems, which can be mitigated by raising the modulation frequency. Because the peak intensity of a PWM illumination can be 100 times that of the average intensity, the indoor solar cell, which has a relatively high series resistance, is expected to underperform. In this paper, the characteristics of a commercial indoor DSSC under PWM illumination are studied. It is found that while PWM illumination at low frequency seriously deteriorates the performance of the DSSC, it recovers at high frequency. The latter feature is not found in indoor amorphous-Si solar cells, and the electrochemical impedance spectroscopy revealed that it stems from the electrochemical nature of some components of the series impedance in the DSSC, offering a key piece of evidence of the superiority for use in the modern indoor application of the DSSC over traditional amorphous-Si solar cells.

Perovskite‐Based Photovoltaics for Artificial Indoor Light Harvesting: A Critical Review

Under artificial indoor light, the development of efficient photovoltaics has attracted massive attention due to the revolutionary growth involving the Internet of Things for riding low‐power wireless electronic gadgets. Among the variety of available photovoltaic technologies such as inorganics (i.e., silicon, copper indium gallium selenide, cadmium telluride), organic photovoltaics, and hybrid organic–inorganic perovskites photovoltaics (PPVCs), the PPVCs have been recognized as the most promising PVCs for indoor light energy harvesting applications. This suitability is related to various factors due to its significant absorption coefficient, tunable bandgap, remarkable defect tolerance, better optoelectronic properties, and straightforward fabrication process. However, several parameters interconnected to materials, processing conditions, architecture, and indoor characterizations need to be optimized to enhance indoor photovoltaic efficiency, stability, and eco‐friendly nature. This review summarizes the latest research trends on organic–inorganic perovskite material‐based indoor PVCs, including the impact of composition tuning, choice of many practical layers, and device structures on their performance. Various challenges are highlighted to address before these indoor PPVCs are available in the commercial market.

2D MXene Additive‐Induced Treatment Enabling High‐Efficiency Indoor Organic Photovoltaics

AbstractThe surge of Internet‐of‐everything applications over the past decade demands the adoption of novel material design and device engineering strategies for the development of state‐of‐the‐art organic photovoltaics (OPVs) in low‐light indoor environments. Owing to their excellent optoelectronic properties, two‐dimensional MXenes possess outstanding potential in this regard. Herein, an unprecedented indoor power conversion efficiency (PCE) of 33.8% under light‐emitting‐diode (LED) illumination (1000‐lx) is secured by additive‐induced treatment of MXene in polymer‐donor:non‐fullerene‐acceptor‐based organic photoactive layer. The remarkable indoor performance of MXene OPVs mainly originates from the enhanced absorption, compact molecular packing, and smooth surface morphology with a reduced number of grain boundaries in the photoactive layer, resulting in an improved fill factor and balanced charge transport and extraction characteristics with suppressed recombination, thereby producing an impressive indoor PCE. In addition, the presence of MXene in the photoactive layer facilitates polaron‐pair dissociation owing to improved free‐charge generation, leading to enhanced photoconductivity. This performance represents the highest PCE among the OPVs measured under indoor illumination. This work highlights the promising prospect of 2D MXene and its composites for indoor light energy harvesting applications.

Color-temperature dependence of indoor organic photovoltaic performance

Organic materials are uniquely suited for indoor light energy harvesting because they absorb mostly in the visible spectrum and the absence of ultraviolet light minimizes their degradation. However, the performance of photovoltaic devices under indoor lighting depends on the correlated color temperatures (CCTs) of the light sources but has not been examined previously. Here we study organic photovoltaics with different combinations of donor and acceptor materials under white light-emitting diode (LED) illumination. The current density – voltage (J - V) measurements were performed under illuminance of 1000 lx at nominal LED CCTs of 3000 K, 4000 K, and 6000 K. Absorption spectra of neat and blended films and device external quantum efficiency were measured. Our results show that active layer absorption in the blue LED emission region determines the short-circuit current density (J sc ) increase from 3000 K to 6000 K CCT; the more the active layer absorbs at 450 nm, the larger the J sc increase under higher CCTs. We find that the normalized fractional absorption of the active layer at 450 nm needs to be > 0.85 to eliminate a decrease in power conversion efficiency as the CCT is varied from 3000 K to 6000 K. This work highlights the unique tunability of organic absorbers that is difficult to achieve in inorganic materials and provides guidance on how to select organic absorbers for specific applications under different indoor illumination conditions. • Study color-temperature dependence of organic photovoltaic performance under white light-emitting diode illumination. • Active layer absorption at 450 nm determines the power conversion efficiency (PCE) under cool white light. • A threshold exists in the 450-nm absorption to eliminate PCE decrease as color-temperature increases. • Analyze color-temperature behavior of high-performance organic photovoltaics.

Integration of fully printed and flexible organic electrolyte-based dual cell supercapacitor with energy supply platform for low power electronics

We report the fabrication of flexible, printed dual cell supercapacitors (DCSCs) and their implementations in energy storage units providing peak power to portable devices. The use of organic electrolytes enhances higher capacity in both potential windows (2.5 V/cell) and the temperature ranges than the aqueous electrolytes, while propylene carbonate retains the advantages of low cost and low toxicity. The device delivered capacitance value between 3 and 4 mF, equivalent series resistance < 2 Ω, and very low leakage current of about 0.1 µA. We demonstrated the integration of an organic photovoltaic module (OPV) with an energy supply platform (ESP) and DCSCs for indoor light energy harvesting and storage. The maximum harvested energy was about 39 mJ. The energy is sufficient to provide peak power to portable devices and sensors. This was confirmed by powering an LED with our energy harvesting system. Mechanical deformation testing of DCSCs shows excellent mechanical stability, so that the device is well suited for flexible energy storage units. In a long-term cyclic stability test, the decrease in capacitance value was only 1% of the initial value after 10,000 cycles, indicating good durability and performance.

Low-Cost Sensors for Indoor PV Energy Harvesting Estimation Based on Machine Learning

With the number of communicating sensors linked to the Internet of Things (IoT) ecosystem increasing dramatically, well-designed indoor light energy harvesting solutions are needed. A first step in this direction would be to be able to accurately estimate the harvestable energy in a specific light environment. However, inside, this energy varies in spectral composition and intensity, depending on the emission source as well as the time of day. These challenging conditions mean that it has become necessary to obtain accurate information about these variations and determine their impact on energy recovery performance. In this context, this manuscript presented a method to apply an innovative energy harvesting estimation method to obtain practical and accurate insight for the design of energy harvesting systems in indoor environments. It used a very low-cost device to obtain spectral information and fed it to supervised machine learning classification methods to recognize light sources. From the recognized light source, a model developed for flexible GaAs solar cells was able to estimate the harvestable energy. To validate this method in real indoor conditions, the estimates were compared to the energy harvested by an energy harvesting prototype. The mean absolute error percentage between estimates and the experimental measurements was less than 5% after more than 2 weeks of observation. This demonstrated the potential of this low-cost estimation system to obtain reliable information to design energetically autonomous devices.

Indoor light energy harvesting for battery-powered sensors using small photovoltaic modules.

As interest in Internet-of-Things (IoT) devices like wireless sensors increases, research efforts have focused on finding ways for these sensors to self-harvest energy from the environment in which they are installed. Photovoltaic (PV) cells or mini-modules are an intuitive choice for harvesting indoor ambient light, even under low light conditions, and using it for battery charging and powering of these devices. Characterizations of battery charging, for small rechargeable batteries from low charge to full charge, have been investigated using PV mini-modules of equal area. We present battery charging results using three different PV technologies, monocrystalline silicon (c-Si), gallium-indium-phosphide (GaInP) and gallium-arsenide (GaAs) under a warm color temperature (3000 K) LED lighting at an illuminance of 1000 lx. Battery charging times are shortest for the more efficient GAInP and GaAs mini-modules whose spectral response are a better match to the LED test source, which contains mostly visible photons, and longest for the less efficient Si cells. As a demonstration, a wireless temperature sensor mote was attached to the charging circuit and operated to determine its power consumption in relation to the available charging power. The mote's maximum power draw was less than the charging power from the least efficient c-Si mini-module. Our findings affirm the feasibility of utilizing PV under typical indoor lighting conditions to power IoT devices.

Efficiency improvement of indoor organic solar cell by optimization of the doping level of the hole extraction layer

Currently, the use of self- and low-powered, small dimension electronic devices for indoor use, such as smart meters, sensors, actuators, and wearable devices, is increasing our standard of living via the Internet of Things technology. Normal power sources are not recommended for these devices because of their small scale; however, an efficient means of powering them is via ambient energy harvesters. Indoor photovoltaic (IPV) cells are a very good power source option due to the ease of accessibility and availability of indoor light. Furthermore, IPV cells based on organic materials are one of the best options due to their good spectral matching and mechanical flexibility. Despite tremendous effort being devoted to the improvement of efficiency, applicability, longevity, and commercial acceptability of organic IPV devices, further research is needed to achieve their integrated use. In an organic IPV cell, the hole extraction layer (HEL) is an important component used to improve the hole extraction ability of the device. An alternative p-type semiconducting material that is cheaper, more environmentally stable, more processable, less sensitive to humidity, and highly conductive, is highly recommended. Therefore, in this work, we have attempted to develop a highly efficient organic IPV cell by optimizing the doping concentration of its HEL. We have used water-stable polyaniline (PANI) (doped with poly (sodium-4-styrenesulfonate) (PSS)) as the HEL because of its good environmental stability, low acidity, low price, and insensitivity to humidity. It has been observed that the indoor light energy harvesting ability of the device is strongly dependent on the doping concentration of its HEL and at an optimized concentration of PSS (100 mg), under the illumination of a 500 lx LED lamp; the device exhibits a power conversion efficiency value of 8.1%.

Power Estimation for Indoor Light Energy Harvesting Systems

The growing interest in indoor light energy harvesting for wireless sensor systems and low-power electronics has created a demand for systematic design methods that optimize the system implementation and component choices for different lighting scenarios. Although the spectrum of light is known to influence the efficiency and output power of a photovoltaic (PV) cell, existing power estimation methods neglect the spectrum. By contrast, the power estimation method proposed in this article takes spectral and intensity information into account. It uses low-cost sensors to measure spectral information and select an appropriate device model based on the classification of the light source. The method is evaluated under different light conditions, including individual light sources, mixed artificial light sources, and mixtures of artificial light and sunlight. The results demonstrate that the proposed implementation selects a reasonable model in most cases, including mixed light source conditions. Using light source specific models for PV panels, the resulting estimation error is low and has clear advantages over methods neglecting spectral information.

Indoor light energy harvesting using infrared LED

ABSTRACT Wireless sensor networks are mostly used at remote locations. Batteries are used to power the wireless sensor networks. Replacing batteries at remote locations is a costly and cumbersome process. Therefore, energy harvesting is a viable solution to charge these rechargeable batteries. This paper describes the design and experimental evaluation of indoor light energy harvesting system using infrared LED array, which consists of IR transmitters and IR receivers in series and parallel combination. Using the proposed design a considerable amount of energy can be obtained from fluorescent lamps or tube lights, which can be used to charge super capacitors or batteries. A DC power of 462 μW has been generated using the proposed design. This system can be used in a wireless sensor network designed for automation of the light/fan in the rooms.

Pilot operation and lifetime assessment for indoor light energy harvesting photovoltaics

Photovoltaic cells for indoor light harvesting have recently attracted considerable attention for low power consumption electronic products due to the rapid growth of the Internet of Things. Dye-sensitized cells (DSC) show tremendous promise in delivering a low-cost, high-manufacturability, and excellent conversion efficiency for various artificial lights to combine with electronics achieving the energy autonomous system. Commercial DSC technology in terms of the reproducibility on cell efficiency and lifetime prediction was discussed to meet requirements of photovoltaic cell market for various applications. The DSC automated pilot line towards industrially relevant manufacturing volumes was described, providing an average efficiency of 13.8% at 1000 lux white LED light and an overall yield of 98.7%. Furthermore, an approach to obtain the database of degradation rate constant for various environmental stresses was proposed according to Arrhenius plots and can be used to predict DSC lifetime for a variety of situations. The lifetime was evaluated to 10.9 years for the indoor situation using the corresponding degradation rate constant.

Silicon nanocrystal hybrid photovoltaic devices for indoor light energy harvesting.

Silicon nanocrystals (SiNCs) featuring size-dependent novel optical and electrical properties have been widely employed for various functional devices. We have demonstrated SiNC-based hybrid photovoltaics (SiNC-HPVs) and proposed several approaches for performance promotion. Recently, owing to the superiorities such as low power operation, high portability, and designability, organic photovoltaics (OPVs) have been extensively studied for their potential indoor applications as power sources. SiNCs exhibit strong light absorption below 450 nm, which is capable of sufficient photocurrent generation under UV irradiation. Therefore, SiNC-HPVs are expected to be preferably used for energy harvesting systems in indoor applications because an indoor light source consists of a shorter wavelength component below 500 nm than solar light. We successfully demonstrated SiNC-HPVs with a PCE as high as 9.7%, corresponding to the output power density of 34.0 μW cm−2 under standard indoor light irradiation (1000 lx). In addition, we have found that SiNC defects working as electron traps influence the electrical properties of SiNCs substantially, a thermal annealing process was conducted towards the suppression of defects and the improvement of the SiNC-HPVs performance.

Self‐Powered Sensors Enabled by Wide‐Bandgap Perovskite Indoor Photovoltaic Cells

AbstractA new approach to ubiquitous sensing for indoor applications is presented, using low‐cost indoor perovskite photovoltaic cells as external power sources for backscatter sensors. Wide‐bandgap perovskite photovoltaic cells for indoor light energy harvesting are presented with the 1.63 and 1.84 eV devices that demonstrate efficiencies of 21% and 18.5%, respectively, under indoor compact fluorescent lighting, with a champion open‐circuit voltage of 0.95 V in a 1.84 eV cell under a light intensity of 0.16 mW cm−2. Subsequently, a wireless temperature sensor self‐powered by a perovskite indoor light‐harvesting module is demonstrated. Three perovskite photovoltaic cells are connected in series to create a module that produces 14.5 µW output power under 0.16 mW cm−2 of compact fluorescent illumination with an efficiency of 13.2%. This module is used as an external power source for a battery‐assisted radio‐frequency identification temperature sensor and demonstrates a read range by of 5.1 m while maintaining very high frequency measurements every 1.24 s. The combined indoor perovskite photovoltaic modules and backscatter radio‐frequency sensors are further discussed as a route to ubiquitous sensing in buildings given their potential to be manufactured in an integrated manner at very low cost, their lack of a need for battery replacement, and the high frequency data collection possible.

Combined Organic Photovoltaic Cells and Ultra Low Power CMOS Circuit for Indoor Light Energy Harvesting

This paper describes an energy harvesting system composed of an organic photovoltaic cell (OPV) connected to a DC–DC converter, designed in a 130 nm Complementary Metal-Oxide-Semiconductor (CMOS) technology, with a quasi- maximum power point tracking (MPPT) algorithm to maximize the system efficiency, for indoor applications. OPVs are an emerging technology with potential for low cost indoor light energy harvesting. The OPV current-voltage curves (I-V) under an irradiance of solar simulator Oriel Sol 3A, at room temperature, are obtained and an accurate electrical model is derived. The energy harvesting system is subjected to four different indoor light sources: 35 W halogen, 3.5 W LED, 5 W LED, and 7 W LED, positioned at three different heights (0.45 m, 0.26 m, and 0.11 m), to evaluate the potential of the system for indoor applications. The measurements showed maximum efficiencies of 60% for 35 W halogen and 45% for 7 W LED at the highest distance (0.45 m) and between 60% (5 W LED) and 70% (35 W halogen), at the shorter distance (0.11 m). Under irradiation, the integrated CMOS circuit presented a maximum efficiency of 75.76%, which is, to the best of the authors’ knowledge, the best reported power management unit (PMU) energy system using organic photovoltaic cells.

Modelling of Indoor Light Energy Harvesting for IoT

Modelling of Indoor Light Energy Harvesting for IoT

Quaternary indoor organic photovoltaic device demonstrating panchromatic absorption and power conversion efficiency of 10%

Recently, while increasing research has been focused toward improving the efficiency of various photovoltaic devices under low light intensities, few studies have reported on multi-donor-, multi-acceptor-based bulk heterojunctions (BHJ). In this study, we have demonstrated the utilization of a quaternary BHJ for indoor light energy harvesting applications. We utilized a PCDTBT:PTB7:PC61BM:PC71BM-based BHJ structure in order to improve the morphology, absorption window, and the charge transport properties of the photovoltaic device. The ability of ternary photovoltaics to attain high power-conversion efficiency (PCE) by improving the morphology and the charge transport properties had already been validated in another study. We show that the advantages of a stable quaternary solar cell can also be achieved with an optimized BHJ composition ratio of 5:5:3:12, which provides a PCE of 10.6%. Our device showed high shunt resistance and low series resistance, thus facilitating appreciable charge extraction even under low-intensity light conditions such as 500 lx white LED illumination.

Low light illumination study on commercially available homojunction photovoltaic cells

Low illumination (10−4suns) and indoor light energy harvesting is needed to meet the demands of zero net energy (ZNE) building, Internet of Things (IoT), and beta-photovoltaic energy harvesting systems to power remote sensors. Photovoltaic (PV) solar cells under low intensity and narrow (±40nm) light spectrum conditions are not well characterized nor developed, especially for commercially available devices and scalable systems. PV operating characteristics under 1 sun illumination decrease at lower light intensity and narrow spectrum conditions (efficiency drops from ∼25% at 100mWopt/cm2 to 2% at 1μWopt/cm2). By choosing a PV with a bandgap that matches the light source operating wavelength, the total system efficiency can be improved. By quantifying losses on homojunction photovoltaics (thermalization and leakage current), we have determined the theoretical optimized efficiency for a set of PV material and a selected set of light sources. We measure single-junction solar cells’ parameters under three different light sources (indoor light and narrow spectrum LED sources) with light intensities ranging from 0.5 to 100μWopt/cm2. Measurements show that indium gallium phosphide (InGaP) PV has the highest surface power density and conversion efficiency (29% under ≈1μWopt/cm2 from a 523nm central peak LED). A beta-photovoltaic experimental study identifies InGaP to be optimized for use with the ZnS:Cu, Al and tritium at STP. The results have guided the selection of PV material for scalable isotope batteries and other low-light energy harvesting systems.