Enhanced Conversion Efficiency Research Articles

Boosting photovoltaic performance for Sb2S3 solar cells by ionic liquid-assisted hydrothermal synthesis

Bulk and surface trap-states in the Sb2S3 films are considered one of the crucial energy loss mechanisms for achieving high photovoltaic performance in planar Sb2S3 solar cells. Because ionic liquid additives offer interesting physicochemical properties to control the synthesis of inorganic material, in this work we propose the addition of 1-Butyl-3-methylimidazolium hydrogen sulfate (BMIMHS) into a Sb2S3 hydrothermal precursor solution as a facile way to fabricate low-defect Sb2S3 solar cells. Lower presence of small particles on the surface, as well as higher crystallinity are demonstrated in the BMIMHS-assisted Sb2S3 films. Moreover, analyses of dark current density-voltage J–V curves, surface photovoltage transient and intensity-modulated photocurrent spectroscopy have suggested that adding BMIMHS results in high-quality Sb2S3 films and a successful defect passivation. Consequently, the best-performing BMIMHS-assisted device exhibits a 15.4% power conversion efficiency enhancement compared to that of control device. These findings show that ionic liquid BMIMHS can effectively be used to obtain high-quality Sb2S3 films with low-defects and improved optoelectronic properties.

Enhancing conversion efficiency of crystalline silicon photovoltaic modules through luminescent down-shifting by using Eu3+-Zn2+complexes

Currently commercial silicon-based solar cells are usually absorbing only a narrow band of sunlight within the visible light range; thus, their conversion efficiency is low. This challenge has been partially improved by using up-converting or down-converting luminescent materials. Amongst those materials, rare earth luminescent materials doped with other rare earth elements have been developed and demonstrated significant improvement of conversion efficiency. This work reports a novel complex Zn0.4Eu0.6(TTA)2phenCl0.6 (named Eu–Zn in short) that have been synthesized through divalent Zn2+ doping into a trivalent Eu3+ luminescent Eu(TTA)3phen matrix. The properties of the Eu–Zn compound have been characterized by using Inductively Coupled Plasma (ICP)-Atomic Emission spectrum, Fourier Transform Infrared (FTIR), Ultraviolet–Visible (UV–Vis) and Photoluminescence (PL) Spectra. The Eu–Zn complex is further integrated in poly(methyl methacrylate) (PMMA) thin films through solution casting and the composite thin film has lower luminescent quantum yield than that of the Eu–Zn complex alone. The Eu–Zn/PMMA composite film as a down-converting luminescent coating layer is constructed in monocrystalline silicon (MCSi, active area of 156 cm2) and polycrystalline silicon (PCSi, active area of 100 cm2) solar cell modules. The external quantum efficiency (EQE) of both MCSi and PCSi modules shows a decrease in the range of 370–400 nm with the increase of Eu–Zn concentration. The conversion efficiency of MCSi cell is improved by 0.37% (from 14.37% to 14.74%) with the concentration of Eu–Zn at 1%.

Enhancing the Efficiency of Dye‐Sensitized Solar Cells (DSSCs) by Nanostructured Ag‐doped ZnO Electrodes

AbstractSilver (Ag) ‐ doped ZnO nanoparticles (0 % to 20 %) were synthesized by the microwave method. The structural, optical, and electrochemical properties were observed through Transmission Electron Microscopy (TEM), X‐ray Diffraction (XRD), Energy Dispersive X‐ray (EDX), UV‐Visible spectroscopy, Photoluminescence, and Cyclic‐Voltammetry (C−V) techniques. The platinum metal counter electrode was replaced by using dip coating, spin coating, and electrochemical method electrodes. The best current‐voltage performance was exhibited by the 5 % Ag‐doped ZnO DSSCs constructed by the electrochemical method counter electrode with a conversion efficiency (η) of 6.19 %, open‐circuit voltage (Voc) of 0.58 V, short circuit current density (Jsc) of 19.12 mA/cm2 and fill factor of 55.08 %. This performance is superior to the counter electrodes made from the spin coating (1.45 %) and dip coating (0.91 %). The higher catalytic behavior of the electrochemical method counter electrode and appearing plasmons peaks in all Ag‐doped ZnO nanoparticles influence the enhancement of current density and overall conversion efficiency.

High‐Crystalline Regioregular Polymer Semiconductor by Thermal Treatment for Thickness Tolerance Organic Photovoltaics

To successfully develop a regioregular polymer, poly[4,8‐bis(5‐(2‐hexyldecyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene][5,5′‐bis(7‐(4‐(2‐butyloctyl)thiophen‐2‐yl)‐6‐fluorobenzo[c][1,2,5]thiadiazol‐4‐yl)‐2,2′‐bithiophene] (PDBD‐FBT), a symmetric monomer synthesized in high yield by tin homo‐coupling reactions. PDBD‐FBT is suitable as a donor material in organic photovoltaics (OPVs) because it shows high crystallinity and strong face‐on packing properties. These properties were amplified by thermal annealing (TA). This causes a power conversion efficiency (PCE) enhancement in PDBD‐FBT‐based OPVs. Using PDBD‐FBT as a polymer donor and 2,2′‐((2Z,2′Z)‐((12,13‐bis(2‐heptylundecyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2‐g]thieno[2′,3′:4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (Y6‐HU) as an electron acceptor, a PCE of 7.91% was achieved without any additive and TA at optimized active layer film thickness of approximately 100 nm. After TA, a PCE of 12.53% was achieved with a 58% increase compared with the reference devices. Owing to the strong crystallinities, trap‐assisted recombination occurs by excessively formed grain boundaries; however, efficient exciton dissociation sufficiently covers these drawbacks. Even in the approximately 340 nm‐thick film condition, this tendency is more pronounced (73% PCE enhancement is observed from 6.17% to 10.69% of PCE in the without and with TA devices, respectively). Our study demonstrates that it is possible to manufacture thickness‐insensitive OPVs based on regioregular polymers with strong crystallinity and face‐on characteristics, thereby providing a solution to the thickness variation of large‐area organic solar cell modules.

Chemical Replacement of Noggin with Dorsomorphin Homolog 1 for Cost-Effective Direct Neuronal Conversion.

The direct conversion of adult human skin fibroblasts (FBs) into induced neurons (iNs) represents a useful technology to generate donor-specific adult-like human neurons. Disease modeling studies rely on the consistently efficient conversion of relatively large cohorts of FBs. Despite the identification of several small molecular enhancers, high-yield protocols still demand addition of recombinant Noggin. To identify a replacement to circumvent the technical and economic challenges associated with Noggin, we assessed dynamic gene expression trajectories of transforming growth factor-β signaling during FB-to-iN conversion. We identified ALK2 (ACVR1) of the bone morphogenic protein branch to possess the highest initial transcript abundance in FBs and the steepest decline during successful neuronal conversion. We thus assessed the efficacy of dorsomorphin homolog 1 (DMH1), a highly selective ALK2-inhibitor, for its potential to replace Noggin. Conversion media containing DMH1 (+DMH1) indeed enhanced conversion efficiencies over basic SMAD inhibition (tSMADi), yielding similar βIII-tubulin (TUBB3) purities as conversion media containing Noggin (+Noggin). Furthermore, +DMH1 induced high yields of iNs with clear neuronal morphologies that are positive for the mature neuronal marker NeuN. Validation of +DMH1 for iN conversion of FBs from 15 adult human donors further demonstrates that Noggin-free conversion consistently yields iN cultures that display high βIII-tubulin numbers with synaptic structures and basic spontaneous neuronal activity at a third of the cost.

Enhanced conversion efficiency of vacancy-related color centers in diamonds grown on a patterned metal surface by chemical vapor deposition

Vacancy-related color centers in diamonds, such as nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers, have good application prospects in solid-state quantum technologies. In various applications, shot noise-limited sensitivity is determined by coherence time and photoluminescence (PL) intensity, which depends on the color center density. However, the conversion efficiencies of impurity atoms to color centers are low and usually increased by electron irradiation, which destroy the lattice structure and create defects leading to decoherence. In this study, we epitaxially grew diamond layers containing color centers on surfaces coated with metal stripes. The PL intensities of NV0, NV−, and SiV− centers located directly above the metal surface were 3.27, 3.47, and 11.15 times higher than those of the diamond epitaxial region. The [N]–[NV] and [Si]–[SiV] conversion efficiencies were 63.26% and 35.68%, respectively, which were comparable to or even better than those achieved by electron irradiation. Moreover, the region above the metal exhibited a high lattice quality, longer transverse relaxation time, higher magnetic field sensitivity, and larger NV−/NV0 ratio. The findings of this study can help advance the existing research on NV-based magnetometers, biofluorescent labeling, and interfacial spin quantum memory and be potentially applied to other vacancy-related color centers, such as germanium-vacancy.

Numerical study of terahertz radiations from difference frequency generation with large spectral tunability and significantly enhanced conversion efficiencies boosted by 1D leaky modes

The nonlinear optical process of difference frequency generation (DFG) is a prominent technique to produce continuous-wave terahertz radiations while its low conversion efficiency calls for substantial enhancement using artificial structures. All-dielectric nanostructures supporting the quasi-bound states in the continuum (QBIC) appear as a promising approach to this end. To achieve the utmost of enhancement, both input lightwaves of the DFG should work at the QBIC conditions and in many cases a spectral tunability of the input wavelength is necessary. All these requirements go beyond the capability of conventional QBIC which can only happen within a narrow bandwidth for a given structure. In this work, we numerically demonstrate that these restrictions can be eliminated by using our recently proposed concept of one-dimensional leaky modes with ultrahigh Q factors and large operation bandwidth. Using an elaborately designed structures in the form of binary waveguide gratings (BWGs) made from LiNbO3 thin film, we demonstrate that a conversion efficiency enhanced by the order of 1011 can be achieved using the BWGs made from LiNbO3, compared to the case of a bare LiNbO3 thin film. Furthermore, enhanced THz generations over a large spectral range can be easily achieved by changing the incident angle of one input light beam while tuning its wavelength to match the requirement for the leaky resonance excitation at that angle.

Extensive enhancement in power conversion efficiency of dye-sensitized solar cell by using Mo-doped TiO2 photoanode

Extensive enhancement in power conversion efficiency of dye-sensitized solar cell by using Mo-doped TiO2 photoanode

(Invited) One-Dimensionally Aligned Quantum Rods for Generation of Highly-Pure Circularly Polarized Light with High Light Intensity

Converting non-polarized visible light (natural light) into circular polarized (CP) light is currently an important issue because of the attractive properties of CP light such as acceleration of photosynthesis and enhancement of conversion efficiency of photovoltaics[1,2]. Until now, various methods for creating CP visible light, such as filtration by circular polarizer, selective reflection by chiral liquid crystal structures, and circular polarized luminescence (CPL) from chiral luminophores[3], have been reported. However, creation of highly-pure CP visible light with high light intensity is still considered as challenging issue. In this presentation, we propose an approach for creating highly-pure CP visible light with high light intensity by converting linearly polarized luminescence (LPL) using quarter-wave plate.In this work, we put spotlight on colloidal semiconductor quantum rods (QRs) because of its unique advantages described as follows: (1) Absorption coefficient and emission quantum yield are relatively high. (2) Sharp emission peaks are expected. (3) Variety of QRs with different emission colors can be excited by irradiation of single-wavelength light. We selected CdSe/CdS core/shell QRs as LPL generating 1D nanostructure. CdSe/CdS core/shell QRs were synthesized by hot-injection method. As shown in Figure 1a, the obtained suspension showed orange-colored strong emission under UV light irradiation. TEM image of the dried sample of the QRs toluene suspension indicates that the average length, average width of the obtained rod-like nanostructures were about 30 nm and 4.5 nm, respectively. After QRs/toluene suspension was mixed with poly(ethylene-co-vinyl acetate) (EVA)/toluene solution, the mixture was casted on glass slide and dried it under air. Then, the prepared composite polymer film was stretched in one direction and was attached on glass slide. When the luminescence from the QRs/EVA stretched film was observed under the linear polarizer placed in parallel direction to the stretching direction, the observed light was brighter than that of perpendicular direction (Figure 1c). By measuring the photoluminescence of parallel (I//) and perpendicular (I⊥) components under depolarized excitation at 450 nm, the QRs/EVA stretched film showed clear LPL property with constant ratio (CR) = 5.4, defined as CR = I// / I⊥ (Figure 1b). Furthermore, when the QRs/EVA stretched film was combined with a quarter-wave plate placed at 45° to the stretching direction and was observed through the right-handed (RH) or left-handed (LH) circular polarizer, brighter light was observed through LH circular polarizer (Figure 1d). By quantitative evaluation of RH- and LH-CP light components, total emission includes 82% of LH-CP light and 18% of RH-CP light (Figure 1e). These results indicate that the combination of the QRs/EVA stretched film and quarter-wave plate generate highly-pure CP light which can be distinguished by the naked eye (Figure 2d). Interestingly, the handedness of CP light can be switched by simply changing the angle between fast axis of the quarter-wave plate and stretching direction of LPL films (Figure 1f). In this presentation, we will also discuss about multiplexing of optical information by using CP light conversion.[1] W. Qin et. al., J. Phys. Chem., 2018, 122, 12566-12571. [2] B. Hu et. al., ACS Photonics, 2017, 4, 2821-2827. [3] P. Duan, M. Liu et. al., Adv. Mater. 2020, 32, 1900110. Figure 1

Enhancement of power conversion efficiency of dye-sensitized solar cell via symmetrical Bi-anchoring organic molecules as co-sensitizer

A strategy has carried to improvise the photovoltaic performance of DSSCs using auxiliary compounds as co-sensitizer along with organic sensitizer. Herein, bi-anchoring metal-free aromatic organic molecules (A-π-A) based co-sensitizer was utilized with organic sensitizer (DTTCY) and a Co 2+/3+ [bnbip] redox couple incorporated PEG-HEC quasi-solid-state electrolyte for an efficient DSSCs. Interestingly, ACY organic co-sensitized device (typically TiO 2 /ACY/DTTCY/Co 2+/3+ [bnbip]/PEG-HEC/Pt) has achieved a maximum power conversion efficiency of 8.3% under AM 1.5 G illumination (100 mW cm −2 ). At the same instance, NCY and PCY co-sensitized devices achieved comparably lower PCE of 7.44% and 6.99% respectively. These results prove that longer π-conjugation and bi-anchoring group of ACY molecules has induced electron injection process on TiO 2 surface. The influences of co-sensitizer are strongly covered the naked spectrum in the UV region and fill the vacant area in TiO 2 that induces a change in Quasi Fermi level of and decreases recombination flanked by photo-anode and oxidized cobalt species. The PCE results of ACY sensitized device are sustained by some electrochemical factors such as Bulk Resistance (R s = 17.23 Ω), Recombination Resistance (R Rec = 18.84 Ω), Charge Transfer Resistance (R CT = 1.136 Ω), Chemical capacitance (C μ = 13.66 μF), Ionic Conductivity (σ = 2.31 E −03 S cm −1 ), electron lifetime (τ n = 52.85 μs), electron transport time (τ d = 3.29.\μs) and collection efficiency (η COL = 93.97 %), rate of reaction constant (K eff = 18.92 s −1 ), Electron Density (n s = 1.21 E +17 cm −3 ), Dielectric constant (D eff = 0.011 mm 2 s -1 ), Dielectric Length (L n = 0.776 mm). The opportunity of trapping the co-sensitizer system functionalizes the anode surface supposed to avoid back electron transfer and dye degradation. The motive of the study is to enhance the photo-ability of metal-free DTTCY sensitizer along with metal-free co-sensitizer and metal-free additives integrated into the blend polymer electrolyte. • Design and synthesis of (A-π-A) based co-sensitizer for DSSCs application. • PEG-HEC polymer with Cobalt redox couple used as an effective QSS electrolyte. • ACY organic co-sensitized device has achieved a maximum PCE of 8.3%. • ACY co-sensitizer reduces recombination reaction in DSSCs.

Energy Conversion Efficiency Enhancement of Polyethylene Glycol and a SiO2 Composite Doped with Ni, Co, Zn, and Sc Oxides

Doping the SiO2 support with Co, Ni, Zn, and Sc improves the thermal conductivity of a hybrid PEG/SiO2 form-stable phase change material (PCM). Doping also improves the energy utilization efficiency and speeds up the charging and discharging rates. The thermal, chemical, and hydrothermal stability of the PEG/Zn-SiO2 and PEG/Sc-SiO2 hybrid materials is better than that of the other doped materials. The phase change enthalpy of PEG/Zn-SiO2 is 147.6 J/g lower than that of PEG/Sc-SiO2, while the thermal conductivity is 40% higher. The phase change enthalpy of 155.8 J/g of PEG/Sc-SiO2 PCM is very close to that of the parent PEG. PEG/Sc-SiO2 also demonstrates excellent thermal stability when subjected to 200 consecutive heating–cooling cycles and outstanding hydrothermal stability when examined under a stream at 120 °C for 2 h. The supercooling of the PEG/Sc-SiO2 system is the lowest among the tested materials. In addition, the developed PCM composite has a high energy storage capacity and high thermal energy storage/release rates.

Revisiting the Classical Wide-Bandgap HOMO and Random Copolymers for Indoor Artificial Light Photovoltaics.

Organic indoor photovoltaics (IPVs) are attractive energy harvesting devices for low-power consumption electronic devices and the Internet of Things (IoTs) owing to their properties such as being lightweight, semitransparent, having multicoloring capability, and flexibility. It is important to match the absorption range of photoactive materials with the emission spectra of indoor light sources that have a visible range of 400-700nm for IPVs to provide sustainable, high-power density. To this end, benzo[1,2-b:4,5-b']dithiophene-based homopolymer (PBDTT) is synthesized as a polymer donor, which is a classical material that has a wide bandgap with a deep highest occupied molecular orbitals (HOMO) level, and a series of random copolymers by incorporating thieno[3,4-c]pyrrole-4,6,-dione (TPD) as a weak electron acceptor unit in PBDTT. The composition of the TPD unit is varied to fine tune the absorption range of the polymers; the polymer containing 70% TPD (B30T70) perfectly covers the entire range of indoor lamps such as light-emitting diodes (LEDs) and fluorescent lamp (FL). Consequently, B30T70 shows a dramatic enhancement of the power conversion efficiency (PCE) from 1-sun (PCE: 6.0%) to the indoor environment (PCE: 18.3%) when fabricating organic IPVs by blending with PC71 BM. The simple, easy molecular design guidelines are suggested to develop photoactive materials for efficient organic IPVs.

Optimization of metal nanoparticles concentration in dye solution to enhance performance of dye sensitized solar cells

In this study, we incorporate metal nanoparticles of AuNP and AgNP into dye N-719 solution in order to enhance the light absorption of dye-sensitized solar cells (DSSCs) device. AuNP or AgNP was mixed into N-719 dye solution by optimized the concentration of metal NPs. The optical property of the mixtures was investigated by use of UV-Vis spectroscopy while the morphology of the solutions was captured by TEM microscopy. The performance of DSSCs was done by J-V measurement equipped with solar simulator under light illumination of 100mW/cm2. Our fabricated DSSC devices show the enhancement of current density and power conversion efficiency (PCE) with the incorporation of metal NPs into dye layer. Addition of gold nanoparticle capped by dodecanethiols (AuDT) 5.66 wt.% reveals the enhancement of PCE devices from 1.58% without AuDT as reference to 2.77% with AuDT. Similar case for the addition of AgSC8 into dye of DSSC gives the same tendencies.

Enhancement of power conversion efficiency by chlorophyll and carotenoid co-sensitization in the biosolar cells

Photosynthetic pigment-based biosolar cells (BSCs) have attracted much attention over the past few years in the field of artificial photosynthesis. To further improve the power conversion efficiency (PCE) of chlorophyll (Chl)-based bilayer BSCs, co-sensitization effects of three carboxylated chromophores, methyl trans-32-carboxy-pyropheophorbide-a (H2Chl-1), methyl 7-deformyl-7-(trans-carboxyethenyl)-pyropheophorbide-b (H2Chl-2), and β-apo-8′-carotenoic acid (Car) were investigated as H2Chl-1:H2Chl-2, H2Chl-1:Car, and H2Chl-2:Car combinations. The homogeneously co-sensitized mesoporous TiO2 (m-TiO2) layer (TiO2–H2Chl:Car) serves as the photoactive and electron extraction layer, while a Chl-a derivative, zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide-a (ZnChl) forms J-type self-aggregation film and acts as electron donor layer. The light absorption and electron injection efficiency of the TiO2 sensitized H2Chl-1:Car blends are better than those of other types of co-sensitization after optimizing the blend ratio of each type. The electron absorption spectrum of TiO2–(H2Chl-1:Car) at the best mass ratio of 10:3 (molar ratio of 12:5) showed wider absorption band in 350–450 nm region compared to the spectrum of sole TiO2–(H2Chl-1). The charge transfer resistance was significantly reduced when TiO2–(H2Chl-1:Car) was applied for BSCs. The best PCE of 2.13% was achieved using TiO2–(H2Chl-1:Car = 10:3), which corresponds to 40% increase of PCE compared to the device using TiO2–(H2Chl-1) without Car.

Highly Efficient and Reliable Semitransparent Perovskite Solar Cells via Top Electrode Engineering

AbstractTransparent electrodes are essential to allow optical transparency for realizing semitransparent perovskite solar cells (ST‐PSCs). This study addresses gallium‐ and titanium‐doped indium oxide (IO:GT) between the electron transport layer (ETL) and top electrode to potentially replace conventional indium tin oxide (ITO) used in inverted ST‐PSCs. The shallower work function (−4.23 eV) of IO:GT than that (−4.69 eV) of conventional ITO contributes to suppressing the formation of the Schottky barrier and enhancing the charge transport at the ETL/cathode interface. By adopting IO:GT, the ST‐PSC exhibits an enhancement in power conversion efficiency (PCE) from 8.59% to 17.90% (certified 17.53%) with an average visible transmittance (AVT) of 21.9%, which is the record PCE at similar AVT among all ST‐PSCs reported to date. Moreover, combining these ST‐PSCs as the top cell, a four‐terminal perovskite–perovskite tandem solar cell is realized, showing a high PCE of 23.35%. Furthermore, the stability of the ST‐PSCs is confirmed excellent, maintaining over 96% of the initial PCE after 1864 h (≈77 days) in air ambient without encapsulation, which is better than the device employing a metal cathode. Therefore, these results demonstrate that the adoption of IO:GT can be a promising route for efficient and stable inverted ST‐PSCs with preferred transparency.

Evaporated Undoped Spiro‐OMeTAD Enables Stable Perovskite Solar Cells Exceeding 20% Efficiency

AbstractThermal evaporation (TE) as a scalable and low‐cost technique for fabrication of organic hole transport materials (HTMs) typically produces low photovoltaic performance and poor device reproducibility in the application of perovskite solar cells (PSCs), and there is a clear need to understand the weaknesses of TE. Here, a versatile manufacturing technology, solvent‐annealing assisted thermal evaporation (SATE), enabling effective modulation of organic film morphology as well as optoelectronic properties, is introduced. The SATE method produces undoped spiro‐OMeTAD layers with high density, good film homogeneity, enhanced conductivity, and remarkable film stability, all of which are superior to that made by conventional TE. In addition, SATE films eliminate the dopant induced degradation mechanism and simultaneously improve the electrical conductivity of undoped HTMs. Significantly, the resulting devices yield a 36% enhancement of power conversion efficiency (PCE) from 14.68% (TE) to 20.02% (SATE), which is the highest reported PCE for evaporated HTMs in n–i–p PSCs. Moreover, unencapsulated PSC devices with SATE demonstrate an impressive environmental and thermal stability by maintaining 85% of initial performance after 2500 h in air with 30% humidity. The high efficiency with simultaneously improved stability demonstrates SATE can be generally applicable to controllable fabrication of organic thin film and reliable devices.

Atomic-scale platinum deposition on photocathodes by multiple redox cycles under illumination for enhanced solar-to-hydrogen energy conversion

The fabrication of photoelectrochemical (PEC) cells using Cu2O, a semiconductor light absorber that responds to infinite sunlight, requires techniques for loading and activating highly efficient cocatalysts to increase the hydrogen production selectivity. However, there has been relatively little interest in techniques for the deposition of efficient catalysts on PEC electrodes that can maximize the surface activation of the light absorption layer for water splitting, because precise control of the Pt loading at the atomic scale is difficult. We designed an intelligent multiple-redox illuminated deposition technique capable of depositing atomic-scale Pt catalysts with optimal performance on the photocathode surface. An Sb:Cu2O/Cu2O/Al:ZnO/TiO2 photocathode with the proposed atomic-scale Pt catalyst has a high photocurrent density of 6.2 mA cm−2 and a more positive onset potential of 0.71 VRHE. In addition, the mass activity of this electrode is 3.35 times higher than that of Pt samples deposited by conventional methods, and the electrode also shows outstanding operational stability. The proposed approach enables a uniform catalyst distribution and position-selective deposition atomic-scale Pt by repeated redox reactions. Consequently, our proposal enables the simultaneous realization of enhanced conversion efficiency and low cost by the consumption of a relatively small quantity of Pt in controllable redox photodeposition.

Formation of Native Inx(O,S)y Buffer through Surface Oxidation of Cu(In,Ga)(S,Se)2 Absorber for Significantly Enhanced Conversion Efficiency of Flexible and Cd‐Free Solar Cell by All‐Dry Process

Herein, flexible, Cd‐free, and all‐dry process Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells on stainless steel (SUS) substrates are developed with manufacturing CIGSSe absorbers fabricated in real production line with large sample size of 0.94 × 1.23 m2. Air‐annealing process under a temperature of 130 °C, 1 atmospheric pressure, and air humidity of about 50% (accelerated oxidizing process) is conducted on absorbers for their oxidized surface. It is demonstrated for the first time that oxidized surface of CIGSSe absorbers after air‐annealing process gives rise to considerable increases in photovoltaic performances of CIGSSe solar cells. This occurs because of formation of native Inx(O,S)y buffer near CIGSSe surface formed after air‐annealing process, which yields self‐forming heterojunction, acting as charge separation and hole‐blocking barrier with increased valence band offset of native Inx(O,S)y/CIGSSe to 1.4 eV, thereby avoiding sputtering damage on CIGSSe surface. Therefore, carrier recombination rates at the interface and depletion regions of the solar cell are reduced, implying improvement of interface and near‐surface qualities. Ultimately, conversion efficiency of 16.7% for flexible, Cd‐free, and all‐dry process CIGSSe solar cell on SUS substrate is attained after the air‐annealing process (130 °C and 6 h) with potential toward Lab‐to‐Fab transition.

Recent Advances on Tin Oxide Electron Transport Layer for High-Performance Perovskite Solar Cells

In recent years, perovskite solar cells (PSCs) have been considered as a game changer for next-generation photovoltaic industry. A surge of attention originates from unprecedentedly rapid enhancement in power conversion efficiency (PCE) to reach over 25%, being competitive with commercialized silicon solar cells. The charge transporting layer, in particular, an electron transport layer (ETL) is one of the key components for high-performance PSCs. The ETL affords efficient extraction of the photo-generated electrons from the perovskite layer, which are subsequently transferred to transparent conduct oxide electrode. Tin oxide (SnO2) is one of the most attractive materials for the ETL due to its wide band gap, high optical transmission, high carrier mobility and high chemical stability. Moreover, the facile low temperature deposition process of SnO2 layer is suitable for mass production as well as versatile applications such as flexible devices. Regardless of excellent intrinsic properties, however, quality of the functional layer and resulting device performance is largely affected by the fabrication process of the material. In this study, we review the studies to utilize the SnO2 ETL for PSCs by adopting various fabrication processes, ultimately to improve efficiency and stability of the PSCs.

Chlorobenzenesulfonic Potassium Salts as the Efficient Multifunctional Passivator for the Buried Interface in Regular Perovskite Solar Cells

AbstractThe interfacial properties for the buried junctions of the perovskite solar cells (PSCs) play a crucial role for the further enhancement of the power conversion efficiency (PCE) and stability of devices. Delicate manipulation of the interface properties such as the defect density, energy alignment, perovskite film quality, etc., guarantees efficient extraction and transport of photogenerated carriers. Herein, chlorobenzenesulfonic potassium salts are presented as a novel multifunctional agent to modify the buried tin oxide (SnO2)/perovskite interface for regular PSCs. The increasing number of carbon‐chlorine bonds (CCl) in 2,4,5‐trichlorobenzenesulfonic potassium (3Cl‐BSAK) exhibit efficient interaction with uncoordinated Sn, effectively filling oxygen vacancies in the SnO2 surface. Importantly, synergistic effects of the functional group‐rich organic anions and the potassium ion are achieved for reduced defect density, carrier recombination, and hysteresis. A champion PCE of 24.27% and the open‐circuit voltage (VOC) up to 1.191 V for modified devices are obtained. The unencapsulated devices maintain 80% of their initial PCE after aging at 80 °C for 800 h in the atmosphere and 95% after aging for 100 d. With 3Cl‐BSAK decoration, a high efficiency semitransparent PSC with a PCE of 12.83% and an average visible light transmittance (AVT) over 27% is also obtained.