Performance comparison of AlGaAs,GaAs and InGaP tunnel junctions for concentrated multijunction solar cells

Four tunnel junction (TJ) designs for multijunction (MJ) solar cells under high concentration are studied to determine the peak tunnelling current and resistance change as a function of the doping concentration. These four TJ designs are: AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs. Time‐dependent and time‐average methods are used to experimentally characterize the entire current–voltage profile of TJ mesa structures. Experimentally calibrated numerical models are used to determine the minimum doping concentration required for each TJ design to operate within a MJ solar cell up to 2000‐suns concentration. The AlGaAs/GaAs TJ design is found to require the least doping concentration to reach a resistance of <10⁻⁴ Ω cm² followed by the GaAs/GaAs TJ and finally the AlGaAs/AlGaAs TJ. The AlGaAs/InGaP TJ is only able to obtain resistances of ≥5 × 10⁻⁴ Ω cm² within the range of doping concentrations studied. Copyright © 2010 John Wiley & Sons, Ltd.     

Thin‐film (25.5 μm) solar cells from layer transfer using porous silicon with 32.7 mA/cm2 short‐circuit current density

We fabricate a 25.5‐μm‐thick monocrystalline Si solar cell with a confirmed power conversion efficiency of 15.4% and an area of 3.88 cm² using a layer transfer process with porous Si. The process is free of photolithography and contains no high‐temperature oxidation steps. We investigate three design features that improve the short‐circuit current density to a value of 32.7 mA/cm² under AM1.5 illumination. The detached back reflector contributes 2 mA/cm², a reduced front‐surface reflectance accounts for an additional 2 mA/cm² and a reduced base doping increases the current density by 1 mA/cm². Copyright © 2002 John Wiley & Sons, Ltd.     

Current transport studies of amorphous n/p junctions and its application in a‐Si:H/HIT‐type tandem cells

This paper presents an understanding of the fundamental carrier transport mechanism in hydrogenated amorphous silicon (a‐Si:H)‐based n/p junctions. These n/p junctions are, then, used as tunneling and recombination junctions (TRJ) in tandem solar cells, which were constructed by stacking the a‐Si:H‐based solar cell on the heterojunction with intrinsic thin layer (HIT) cell. First, the effect of activation energy (E_a) and Urbach parameter (E_u) of n‐type hydrogenated amorphous silicon (a‐Si:H(n)) on current transport in an a‐Si:H‐based n/p TRJ has been investigated. The photoluminescence spectra and temperature‐dependent current–voltage characteristics in dark condition indicates that the tunneling is the dominant carrier transport mechanism in our a‐Si:H‐based n/p‐type TRJ. The fabrication of a tandem cell structure consists of an a‐Si:H‐based top cell and an HIT‐type bottom cell with the a‐Si:H‐based n/p junction developed as a TRJ in between. The development of a‐Si:H‐based n/p junction as a TRJ leads to an improved a‐Si:H/HIT‐type tandem cell with a better open circuit voltage (V_oc), fill factor (FF), and efficiency. The improvements in the cell performance was attributed to the wider band‐tail states in the a‐Si:H(n) layer that helps to an enhanced tunneling and recombination process in the TRJ. The best photovoltage parameters of the tandem cell were found to be V_oc = 1430 mV, short circuit current density = 10.51 mA/cm², FF = 0.65, and efficiency = 9.75%. Copyright © 2015 John Wiley & Sons, Ltd.     

四结叠层太阳电池中AlGaAs/GaAs隧穿结的特性和表现

III-V族化合物叠层太阳电池是具有超高转换效率的第三代新型太阳电池。四结叠层电池GaInP/GaAs/InGaAs/Ge,各子电池的带隙分别为1.8, 1.4, 1.0, 0.7(ev)。为了使各子电池之间电流匹配,在各子电池之间以隧穿结互相连接。本文主要探索研究了四结叠层电池GaInP/GaAs/InGaAs/Ge隧穿结的特性,三个隧穿结的材料选取,探讨了隧穿结对整体叠层电池的特性的补偿作用,对各子电池电流密度的影响,以及在此基础上对整体电池效率的增加。选用AlGaAs/GaAs作为隧穿结运用PC1D进行电池的整体模拟仿真,得到各子电池电流密度分别为16.02mA/cm²,17.12 mA/cm²,17.75 mA/cm²,17.45 mA/cm²,电池在AM0下的开路电压Voc为3.246V,转换效率为33.9%。     

Fabrication of Large‐Scale Single‐Crystalline PrB6 Nanorods and Their Temperature‐Dependent Electron Field Emission

A simple catalysis‐free approach that utilises a gas–solid reaction for the synthesis of large‐scale single‐crystalline PrB₆ nanorods using Pr and BCl₃ as starting materials is demonstrated. The nanorods exhibit a low turn‐on electric field (2.80 V µ‐b;m^?1 at 10 µ‐b;A cm^?2), a low threshold electric field (6.99 V µ‐b;m^?1 at 1 mA cm^?2), and a high current density (1.2 mA cm^?2 at 7.35 V µ‐b;m^?1) at room temperature (RT). The turn‐on and threshold electric field are found to decrease clearly from 2.80 to 0.95 and 6.99 to 3.55 V µ‐b;m^?1, respectively, while the emission current density increases significantly from 1.2 to 13.8 mA cm^?2 (at 7.35 V µ‐b;m^?1) with an increase in the ambient temperature from RT to 623 K. The field enhancement factor, emission current density, and the dependence of the effective work function with temperature are investigated. The possible mechanism of the temperature‐dependent emission from PrB₆ nanorods is discussed.     

Pushing the limits of concentrated photovoltaic solar cell tunnel junctions in novel high‐efficiency GaAs phototransducers based on a vertical epitaxial heterostructure architecture

A monolithic compound semiconductor phototransducer optimized for narrow‐band light sources was designed for achieving conversion efficiencies exceeding 50%. The III‐V heterostructure was grown by metal‐organic chemical vapor deposition, based on the vertical stacking of 5 partially absorbing GaAs n/p junctions connected in series with tunnel junctions. The thicknesses of the p‐type base layers of the diodes were engineered for optimal absorption and current matching for an optical input with wavelengths centered near 830 nm. Devices with active areas of ~3.4 mm² were fabricated and tested with different emitter gridline spacings. The open circuit voltage (Voc) of the electrical output is five times or more than that of a single GaAs n/p junction under similar illumination. The device architecture allows for improved Voc generation in the individual base segments because of efficient carrier extraction while simultaneously maintaining a complete absorption of the input photons with no needs for complicated fabrication processes or reflecting layers. With illumination powers in the range of a few 100 mW, the measured fill factor (FF) varied between 88 and 89%, and the Voc reached over 5.75 V. The data also demonstrated that a proper combination of highly doped emitter and window layers without gridlines is adequate for sustaining such FF values for optical input powers of several hundred milliwatts. As the optical input power is further increased and approaches 2 W (intensities ~58 W/cm²), the multiple tunnel junctions sequentially exceed their peak current densities in the case for which typical (n++)GaInP/ (p++)AlGaAs concentrated photovoltaic tunnel junctions are used. Lower bandgap tunnel junctions designed with improved peak current densities result in phototransducer devices having high FF and conversion efficiencies for up to 5 W optical input powers (intensities ~144 W/cm²). Measurements at different temperatures revealed a Voc reduction of −6 mV/°C at ~59 W/cm². Copyright © 2015 John Wiley & Sons, Ltd.     

Low-temperature processing of shallow junctions using epitaxial and polycrystalline CoSi2

Cobalt disilicide is grown epitaxially on (100) Si from a 15 nm Co/2 nm Ti bilayer by rapid thermal annealing (RTA) at 900°C. Polycrystalline CoSi₂ is grown on (100) Si using a 15 nm Co layer and the same annealing condition. Silicide/p⁺-Si/n-Si diodes are made using the silicide as dopant source:¹¹B⁺ ions are implanted at 3.5–7.5 kV and activated by RTA at 600–900°C. Shallow junctions with total junction depth (silicide plus p⁺ region) measured by high-resolution secondaryion mass spectroscopy of 100 nm are fabricated. Areal leakage current densities of 13 nA/cm² and 2 nA/cm² at a reverse bias of -5V are obtained for the epitaxial silicide and polycrystalline silicide junctions, respectively, after 700°C post-implant annealing.     

Highly‐efficient Cd‐free CuInS2 thin‐film solar cells and mini‐modules with Zn(S,O) buffer layers prepared by an alternative chemical bath process

Recent progress in fabricating Cd‐ and Se‐free wide‐gap chalcopyrite thin‐film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CBD) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (E_g = 3·6–3·8 eV) than the conventional buffer material CdS (E_g = 2·4 eV) currently used in chalcopyrite‐based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd‐free solar cell devices with increased spectral response in the blue wavelength region if low‐gap chalcopyrites are used. Suitable conditions for reproducible deposition of good‐quality Zn(S,O) thin films on wide‐gap CuInS₂ (‘CIS’) absorbers have been identified for an alternative, low‐temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ∼15 nm. The high transparency of this Zn(S,O) buffer layer in the short‐wavelength region leads to an increase of ∼1 mA/cm² in the short‐circuit current density of corresponding CIS‐based solar cells. Active area efficiencies exceeding 11·0% (total area: 10·4%) have been achieved for the first time, with an open circuit voltage of 700·4 mV, a fill factor of 65·8% and a short‐circuit current density of 24·5 mA/cm² (total area: 22·5 mA/cm²). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini‐modules on 5 × 5 cm² substrates have been prepared and already reach an efficiency (active area: 17·2 cm²) of above 8%. Copyright © 2006 John Wiley & Sons, Ltd.     

Simulation of double junction In0.46Ga0.54N/Si tandem solar cell

A comprehensive study of high efficiency In_0.46Ga_0.54N/Si tandem solar cell is presented. A tunnel junction (TJ) was needed to interconnect the top and bottom sub-cells. Two TJ designs, integrated within this tandem: GaAs(n⁺)/GaAs(p⁺) and In_0.5Ga_0.5N(n⁺)/Si(p⁺) were considered. Simulations of GaAs(n⁺)/GaAs(p⁺) and In_0.5Ga_0.5N (n⁺)/Si(p⁺) TJ I-V characteristics were studied for integration into the proposed tandem solar cell. A comparison of the simulated solar cell I-V characteristics under 1 sun AM1.5 spectrum was discussed in terms of short circuit current density (J_sc), open circuit voltage (V_OC), fill factor (FF) and efficiency (η) for both tunnel junction designs. Using GaAs(n⁺)/GaAs(p⁺) tunnel junction, the obtained values of J_sc = 21.74 mA/cm², V_OC= 1.81 V, FF = 0.87 and η = 34.28%, whereas the solar cell with the In_0.5Ga_0.5N/Si tunnel junction reported values of J_sc = 21.92 mA/cm², V_OC = 1.81 V, FF = 0.88 and η = 35.01%. The results found that required thicknesses for GaAs(n⁺)/GaAs(p⁺) and In_0.5Ga_0.5N (n⁺)/Si(p⁺) tunnel junctions are around 20 nm, the total thickness of the top InGaN can be very small due to its high optical absorption coefficient and the use of a relatively thick bottom cell is necessary to increase the conversion efficiency.     

Stable,Glassy, and Versatile Binaphthalene Derivatives Capable of Efficient Hole Transport,Hosting, and Deep‐Blue Light Emission

Organic light‐emitting diodes (OLEDs) have great potential applications in display and solid‐state lighting. Stability, cost, and blue emission are key issues governing the future of OLEDs. The synthesis and photoelectronics of a series of three kinds of binaphthyl (BN) derivatives are reported. BN_1–3 are “melting‐point‐less” and highly stable materials, forming very good, amorphous, glass‐like films. They decompose at temperatures as high as 485–545 °C. At a constant current density of 25 mA cm^?2, an ITO/BN₃/Al single‐layer device has a much‐longer lifetime (>80 h) than that of an ITO/NPB/Al single‐layer device (8 h). Also, the lifetime of a multilayer device based on BN₁ is longer than a similar device based on NPB. BNs are efficient and versatile OLED materials: they can be used as a hole‐transport layer (HTL), a host, and a deep‐blue‐light‐emitting material. This versatility may cut the cost of large‐scale material manufacture. More importantly, the deep‐blue electroluminescence (emission peak at 444 nm with CIE coordinates (0.16, 0.11), 3.23 cd A^?1 at 0.21 mA cm^?2, and 25200 cd m^?2 at 9 V) remains very stable at very high current densities up to 1000 mA cm^?2.     

Fabrication and analysis of multijunction solar cells with a quantum dot (In)GaAs junction

InAs quantum dots (QDs) have been incorporated to bandgap engineer the (In)GaAs junction of (In)GaAs/Ge double‐junction solar cells and InGaP/(In)GaAs/Ge triple‐junction solar cells on 4‐in. wafers. One sun AM0 current–voltage measurement shows consistent performance across the wafer. Quantum efficiency analysis shows similar aforementioned bandgap performance of baseline and QD solar cells, whereas integrated sub‐band gap current of 10 InAs QD layers shows a gain of 0.20 mA/cm². Comparing QD double‐junction solar cells and QD triple‐junction solar cells to baseline structures shows that the (In)GaAs junction has a V_oc loss of 50 mV and the InGaP 70 mV. Transmission electron microscopy imaging does not reveal defective material and shows a buried QD density of 10¹¹ cm⁻², which is consistent with the density of QDs measured on the surface of a test structure. Although slightly lower in efficiency, the QD solar cells have uniform performance across 4‐in. wafers. Copyright © 2013 John Wiley & Sons, Ltd.     

Molecular Engineering of Blue Fluorescent Molecules Based on Silicon End‐Capped Diphenylaminofluorene Derivatives for Efficient Organic Light‐Emitting Materials

Blue fluorescent materials based on silicone end‐capped 2‐diphenylaminofluorene derivatives are synthesized and characterized. These materials are doped into a 2‐methyl‐9,10‐di‐[2‐naphthyl]anthracene host as blue dopant materials in the emitting layer of organic light‐emitting diode devices bearing a structure of ITO/DNTPD (60 nm)/NPB (30 nm)/emitting layer (30 nm)/Alq₃ (20 nm)/LiF (1.0 nm)/Al (200 nm). All devices exhibit highly efficient blue electroluminescence with high external quantum efficiencies (3.47%–7.34% at 20 mA cm^?2). The best luminous efficiency of 11.2 cd A^?1 and highest quantum efficiency of 7.34% at 20 mA cm^?2 are obtained in a device with CIE coordinates (0.15, 0.25). A deep‐blue OLED with CIE coordinates (0.15, 0.14) exhibits a luminous efficiency of 3.70 cd A^?1 and quantum efficiency of 3.47% at 20 mA cm^?2.     

Zr‐Doped Indium Oxide (IZRO) Transparent Electrodes for Perovskite‐Based Tandem Solar Cells

Parasitic absorption in transparent electrodes is one of the main roadblocks to enabling power conversion efficiencies (PCEs) for perovskite‐based tandem solar cells beyond 30%. To reduce such losses and maximize light coupling, the broadband transparency of such electrodes should be improved, especially at the front of the device. Here, the excellent properties of Zr‐doped indium oxide (IZRO) transparent electrodes for such applications, with improved near‐infrared (NIR) response, compared to conventional tin‐doped indium oxide (ITO) electrodes, are shown. Optimized IZRO films feature a very high electron mobility (up to ≈77 cm² V^?1 s^?1), enabling highly infrared transparent films with a very low sheet resistance (≈18 Ω □^?1 for annealed 100 nm films). For devices, this translates in a parasitic absorption of only ≈5% for IZRO within the solar spectrum (250–2500 nm range), to be compared with ≈10% for commercial ITO. Fundamentally, it is found that the high conductivity of annealed IZRO films is directly linked to promoted crystallinity of the indium oxide (In₂O₃) films due to Zr‐doping. Overall, on a four‐terminal perovskite/silicon tandem device level, an absolute 3.5 mA cm^?2 short‐circuit current improvement in silicon bottom cells is obtained by replacing commercial ITO electrodes with IZRO, resulting in improving the PCE from 23.3% to 26.2%.     

Efficient Organic Tandem Solar Cells based on Small Molecules

In this paper, two vacuum processed single heterojunction organic solar cells with complementary absorption are described and the construction and optimization of tandem solar cells based on the combination of these heterojunctions demonstrated. The red‐absorbing heterojunction consists of C₆₀ and a fluorinated zinc phthalocyanine derivative (F4‐ZnPc) that leads to a 0.1–0.15 V higher open circuit voltage V_oc than the commonly used ZnPc. The second heterojunction incorporates C₆₀ and a dicyanovinyl‐capped sexithiophene derivative (DCV6T) that mainly absorbs in the green. The combination of both heterojunctions into one tandem solar cell leads to an absorption over the whole visible range of the sun spectrum. Thickness variations of the transparent p‐doped optical spacer between both subcells in the tandem solar cell is shown to lead to a significant change in short circuit current density j_sc due to optical interference effects, whereas V_oc and fill factor are hardly affected. The maximum efficiency η of about 5.6% is found for a spacer thickness of 150‐165 nm. Based on the optimized 165nm thick spacer, effects of intensity and angle of illumination, and temperature on a tandem device are investigated. Variations in illumination intensity lead to a linear change in j_sc over three orders of magnitude and a nearly constant η in the range of 30 to 310 mW cm^?2. Despite the stacked heterojunctions, the performance of the tandem device is robust against different illumination angles: j_sc and η closely follow a cosine behavior between 0° and 70°. Investigations of the temperature behavior of the tandem device show an increase in η of 0.016 percentage points per Kelvin between ?20 °C and 25 °C followed by a plateau up to 50 °C. Finally, further optimization of the tandem stack results in a certified η of (6.07 ± 0.24)% on (1.9893 ± 0.0060)cm² (Fraunhofer ISE), i.e., areas large enough to be of relevance for modules.     

Overcoming the poor short wavelength spectral response of CdS/CdTe photovoltaic modules via luminescence down‐shifting: ray‐tracing simulations

The short‐wavelength response of cadmium sulfide/cadmium telluride (CdS/CdTe) photovoltaic (PV) modules can be improved by the application of a luminescent down‐shifting (LDS) layer to the PV module. The LDS layer contains a mixture of fluorescent organic dyes that are able to absorb short‐wavelength light of λ < 540 nm, for which the PV module exhibited low external quantum efficiency (EQE), and re‐emit it at a longer wavelength (λ > 540 nm), where the solar cell EQE is high. Ray‐tracing simulations indicate that a mixed LDS layer containing three dyes could lead to an increase in the short‐circuit current density from J_sc = 19.8 mA/cm² to J_sc = 22.9 mA/cm² for a CdS/CdTe PV module. This corresponds to an increase in conversion efficiency from 9.6% to 11.2%. This indicates that a relative increase in the performance of a production CdS/CdTe PV module of nearly 17% can be expected via the application of LDS layers, possibly without any making any alterations to the solar cell itself. Copyright © 2006 John Wiley & Sons, Ltd.     

Increase in external quantum efficiency of encapsulated silicon solar cells from a luminescent down‐shifting layer

This paper reports the external quantum efficiency (EQE) of encapsulated screen‐printed crystalline silicon solar cells, where the encapsulation includes a layer of luminescent down‐shifting (LDS) molecules. At wavelengths less than 400 nm, the inclusion of the LDS molecules increases the EQE from near zero to, at most, 40%. The increase in EQE corresponds to a rise in short‐circuit current density of 0·37 ± 0·13 mA/cm² under the AM1‐5g spectrum. Copyright © 2008 John Wiley & Sons, Ltd.     

Ion-assisted molecular beam epitaxy of GaAs on Si(100)

GaAs was grown by molecular beam epitaxy (MBE) and ion-assisted MBE on Si(100) substrates. Three-dimensional (3D) island nucleation, observed during MBE growth, was eliminated during ion-assisted MBE when the ion energyE was >25 eV and the product ofE and the current densityJ was ≈6-12 eV mA/cm². IncreasingEJ to ≈15 eV mA/ cm² resulted in excessive ion damage. Decreasing the substrate temperature from 280 to 580° C during ion-assisted MBE yielded a slight decrease in surface roughness, and flatter surfaces were obtained for lower As⁴/Ga flux ratios. The suppression of 3D island nucleation led to an improvement in the crystalline perfection of thicker GaAs films. For example, the x-ray diffraction rocking-curve full-width-at-half-maximum values for 0.5 μm thick films grown at 380° C decreased from 1700 arcsec to 1350 arcsec when ion irradiation was used during nucleation. IAMBE allowed nucleation of thin, relatively flat-surfaced GaAs films even at 580° C, resulting in FWHM values of 1850 arcsec for 0.14 /μm thick films.     

Evaluating the Critical Thickness of TiO2 Layer on Insulating Mesoporous Templates for Efficient Current Collection in Dye‐Sensitized Solar Cells

In this paper, a way of utilizing thin and conformal overlayer of titanium dioxide on an insulating mesoporous template as a photoanode for dye‐sensitized solar cells is presented. Different thicknesses of TiO₂ ranging from 1 to 15 nm are deposited on the surface of the template by atomic layer deposition. This systematic study helps unraveling the minimum critical thickness of the TiO₂ overlayer required to transport the photogenerated electrons efficiently. A merely 6‐nm‐thick TiO₂ film on a 3‐μm mesoporous insulating substrate is shown to transport 8 mA/cm² of photocurrent density along with ≈900 mV of open‐circuit potential when using our standard donor‐π‐acceptor sensitizer and Co(bipyridine) redox mediator.     

p‐CuO/n‐Si heterojunction solar cells with high open circuit voltage and photocurrent through interfacial engineering

Heterojunction solar cells of p‐type cupric oxide (CuO) and n‐type silicon (Si), p‐CuO/n‐Si, have been fabricated using conventional sputter and rapid thermal annealing techniques. Photovoltaic properties with an open‐circuit voltage (V_oc) of 380 mV, short circuit current (J_sc) of 1.2 mA/cm², and a photocurrent of 2.9 mA/cm² were observed for the solar cell annealed at 300 °C for 1 min. When the annealing duration was increased, the photocurrent increased, but the V_oc was found to reduce because of the degradation of interface quality. An improvement in the V_oc resulting to a record value of 509 mV and J_sc of 4 mA/cm² with a high photocurrent of ~12 mA/cm² was achieved through interface engineering and controlling the phase transformation of CuO film. X‐ray diffraction, X‐ray photoelectron spectroscopy, and high‐resolution transmission electron microscopy analysis have been used to investigate the interface properties and crystal quality of sputter‐deposited CuO thin film. The improvement in V_oc is mainly due to the enhancement of crystal quality of CuO thin film and interface properties between p‐CuO and n‐Si substrate. The enhancement of photocurrent is found to be due to the reduction of carrier recombination rate as revealed by transient photovoltage spectroscopy analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Efficient and Durable 3D Self‐Supported Nitrogen‐Doped Carbon‐Coupled Nickel/Cobalt Phosphide Electrodes: Stoichiometric Ratio Regulated Phase‐ and Morphology‐Dependent Overall Water Splitting Performance

The construction of a novel 3D self‐supported integrated Ni_xCo_2?xP@NC (0 < x < 2) nanowall array (NA) on Ni foam (NF) electrode constituting highly dispersed Ni_xCo_2?xP nanoparticles, nanorods, nanocapsules, and nanodendrites embedded in N‐doped carbon (NC) NA grown on NF is reported. Benefiting from the collective effects of special morphological and structural design and electronic structure engineering, the Ni_xCo_2?xP@NC NA/NF electrodes exhibit superior electrocatalytic performance for water splitting with an excellent stability in a wide pH range. The optimal NiCoP@NC NA/NF electrode exhibits the best hydrogen evolution reaction (HER) activity in acidic solution so far, attaining a current density of 10 mA cm^?2 at an overpotential of 34 mV. Moreover, the electrode manifests remarkable performances toward both HER and oxygen evolution reaction in alkaline medium with only small overpotentials of 37 mV at 10 mA cm^?2 and 305 mV at 50 mA cm^?2, respectively. Most importantly, when coupling with the NiCoP@NC NA/NF electrode for overall water splitting, an alkali electrolyzer delivers a current density of 20 mA cm^?2 at a very low cell voltage of ≈1.56 V. In addition, the NiCoP@NC NA/NF electrode has outstanding long‐term durability at j = 10 mA cm^?2 with a negligible degradation in current density over 22 h in both acidic and alkaline media.