One-sun Illumination Research Articles

Double-layered hydrogels based on phase change material and pen ink for continuous and efficient solar-driven seawater desalination

A novel double-layered hydrogel based on the polyacrylamide matrix, pen ink, and phase-change microcapsules was developed to construct a hydrogel-based evaporator for efficient and continuous seawater desalination. The n-eicosane (core)@crystalline TiO2 (shell) phase-change microcapsules were fabricated through interfacial polycondensation, and the resulting phase-change microcapsules obtained a considerably high latent-heat capacity of 187 J·g−1. The upper layer of the hydrogel exhibits a high solar absorptivity of over 90 % due to the introduction of pen ink as a solar absorber, which helps the hydrogel-based evaporator to gain an excellent photothermal energy conversion capability. A high evaporation efficiency of 93.89 % was obtained for the developed hydrogel-based evaporator along with a high evaporation rate of 1.85 kg·m−2·h−1 under one-sun illumination. The phase-change microcapsules dispersed in the lower layer of the hydrogel can act as a latent heat-storage unit to store a great quantity of photothermal energy through melting phase change by the phase change material core. This imparts a consecutive evaporation capability to the developed hydrogel-based evaporator. As a result, its water production was increased by 11 % under 50-min one-sun illumination and 50-min non-illumination.

Understanding the effect of the condensation temperature on solar-driven reverse distillation for enhanced water production

Reverse distillation driven by solar energy decouples light-incoming and evaporation–condensation regions that are integrated together in conventional solar distillation, thereby providing diverse choices in materials and structures for enhancing vapor condensation. However, detailed experiments and discussion are scarce in exploring how condensation temperature influences the solar-to-water energy conversion efficiency in the reverse-distillation process and may thus constrict the further understanding and application in water production processes. A common impression is that a low temperature is good for vapor condensation and performance improvement but that may not be the case. An interesting conclusion from both experimental and theoretical exploration in this research is that the efficiency of the reverse-distillation device first increases and then decreases with the condensation temperature, indicating an optimal condensation temperature for obtaining the best water production performance. In indoor experiments with one-sun illumination, the reverse-distillation device with natural air cooling shows a distillate yield of 1.04 kg⋅m−2⋅h−1 and a solar-to-water energy conversion efficiency of 68.8 %, which is 9.4 % and 6.3 % more than that of a device with enhanced cooling by water flow and inhibited cooling by thermal insulation, respectively. In the outdoor experiments, the increase in efficiency using natural air cooling is 4.9 % and 7.1 % compared with the enhanced and inhibited cooling measures, respectively. The conclusion is further explained from the perspective of heat-and-mass transfer, which may provide meaningful guidance for designing a high-efficiency reverse-distillation system. In future water production, cooling measures should be cautiously considered according to the device structure and the actual working conditions to achieve better performance.

(Invited) Polymeric Carbon Nitride for Photocatalytic Overall Water Splitting

Photocatalytic overall water splitting can be achieved using Z-scheme systems that mimic natural photosynthesis by combining dissimilar semiconductors in series. However, coupling well-suited H2- and O2-evolving components remains challenging. Here, we fabricate a Z-scheme system for photocatalytic overall water splitting based on boron-doped, nitrogen-deficient carbon nitride two-dimensional (2D) nanosheets. We prepare ultrathin carbon nitride nanosheets with varying levels of boron dopants and nitrogen defects, which leads to nanosheets that can act as either H2- or O2-evolving photocatalysts. Using an electrostatic self-assembly strategy, the nanosheets are coupled to obtain a 2D/2D polymeric heterostructure. Owing to their ultrathin nanostructures, strong interfacial interaction and staggered band alignment, a Z-scheme route for efficient charge-carrier separation and transfer is realized. The obtained heterostructure achieves stoichiometric H2 and O2 evolution in the presence of Pt and Co(OH)2 co-catalysts, and the solar-to-hydrogen efficiency reaches 1.16% under one-sun illumination.

(Invited) Nanowires from Dilute Nitride and Dilute Bismide Alloys for Nanophotonics

GaAs-based nanowires (NWs) have a great potential for applications in photonics and optoelectronics, partly owing to flexibility in band structure engineering via alloying, strain and structural polymorphism. Among promising GaAs-based materials for device applications are highly mismatched GaNAs and GaAsBi alloys. The giant bowing in the bandgap energy characteristic for these materials allows easy tuning of emission wavelengths, while other modifications of their electronic structure promise to improve performance of infrared lasers and solar cells. In this talk we will review our recent results related to the electronic properties of novel GaNAs and GaAsBi NWs and provide several examples highlighting their advantages.First of all, we will show that a GaNAs-based mutishell NW can be used as an efficient coherent photon source, where the NW acts both as a miniaturized optical resonator and as a photonic gain medium. Its wavelength can be efficiently tuned by minor changes in N composition, e.g. down to 1 µm with only 2.5 % of nitrogen [1]. The lasing mode is found to arise from the fundamental HE11a mode of the Fabry-Perot cavity from a single NW, exhibiting optical polarization along the NW axis. Moreover, due to superior nonlinear properties of GaNAs, self-frequency conversion of the stimulated emission through second harmonic generation and sum-frequency generation is observed, providing coherent light emission in the cyan-green range.Secondly, we will demonstrate that alloying of GaAs with N and/or Bi leads to the formation of self-assembled quantum dots (QDs) embedded in NWs and, therefore, is an efficient way to fabricate hybrid QD-NW structures with high optical quality. In the case of dilute nitrides, optically active and highly localized QD states are formed due to local fluctuations in N composition [2], whereas in dilute bismides they are caused by Bi segregation at twin planes [3]. Such QDs act as single photon emitters, promising for application in quantum communication technologies.And finally, we will show that favorable band alignment at the interface between a dilute nitride alloy and parental N-free material leads to very efficient energy upconversion due to two-step two-photon absorption in the related NW heterostructures, with the efficiency of this process being among the highest reported in semiconductor nanostructures. Specifically, we show [4] that, in radial GaAs(P)/GaNAs(P) core/shell NW heterostructures, the upconversion efficiency increases by 500 times as compared with that of the constituent materials, even under an excitation power as low as 100 mW/cm2 that is comparable to the one-sun illumination. The upconversion efficiency can be further improved by 8 times through engineering the electric-field distribution of the excitation light inside the NWs so that light absorption is maximized within the desired region of the heterostructure.

Advanced Interface Engineering in Gradient Core/Shell Quantum Dots Enables Efficient Photoelectrochemical Hydrogen Evolution.

Semiconductor core/shell quantum dots (QDs) are considered promising building blocks to fabricate photoelectrochemical (PEC) cells for the direct conversion of solar energy into hydrogen (H2). However, the lattice mismatch between core and shell in such QDs results in undesirable defects and severe carrier recombination, limiting photo-induced carrier separation/transfer and solar-to-fuel conversion efficiency. Here, an interface engineering approach is explored to minimize the core-shell lattice mismatch in CdS/CdSexS1-x (x = 0.09-1) core/shell QDs (g-CSG). As a proof-of-concept, PEC cells based on g-CSG QDs yield a remarkable photocurrent density of 13.1mAcm-2 under AM 1.5 G one-sun illumination (100mWcm-2), which is ≈54.1% and ≈33.7% higher compared to that in CdS/CdSe0.5S0.5 (g-CSA) and CdS/CdSe QDs (g-CS), respectively. Theoretical calculations and carrier dynamics confirm more efficient carrier separation and charge transfer rate in g-CSG QDs with respect to g-CSA and g-CS QDs. These results are attributed to the minimization of the core-shell lattice mismatch by the cascade gradient shell in g-CSG QDs, which modifies carrier confinement potential and reduces interfacial defects. This work provides fundamental insights into the interface engineering of core/shell QDs and may open up new avenues to boost the performance of PEC cells for H2 evolution and other QDs-based optoelectronic devices.

Salting-out/sacrificial template strategy for the preparation of hydrogels as efficient solar evaporators

Hydrogels have recently emerged as promising solar evaporators due to their exceptional high evaporation rates. However, the high costs and complexity associated with the conventional freezing-thawing processes pose challenges that hinder their widespread application in large-scale solar evaporation systems. Herein, we present the successful attempt to prepare hydrogel-based solar evaporators using a salting-out/sacrificial template strategy, where salt particles serve as both salting-out agents and sacrificial templates. Without the need for freezing processes, we successfully synthesized polyvinyl alcohol (PVA) hydrogels, incorporating copper oxide and antimony-doped tin oxide particles as solar absorbers. It is demonstrated that the salting-out (Hofmeister) effect enables the cross-linking of PVA polymeric chains, imparting significant mechanical strength and durability to the hydrogels. Meanwhile, the use of salt particles as sacrificial templates creates well-developed microchannels of 100–300 μm within the hydrogels, enabling rapid water delivery. These hydrogels exhibited a solar-weighted absorptivity of 93.4 % and achieved solar evaporation rates exceeding 3.0 kg m-2h−1 under one-sun illumination. Notably, their performance is comparable to that of state-of-the-art hydrogels prepared using freezing-thawing methods. As such, this proposed strategy holds great promise for the large-scale and cost-effective production of hydrogels as high-performance solar evaporators.

Tailoring the interface by a multifunctional amphiphilic molecule enabled 24.84%-efficiency and stable perovskite solar cells

Surface defects are detrimental to the performance and stability of perovskite solar cells (PSCs). Herein, an amphiphilic molecule of tert-butyl carbazate (TBC) with multiple functional groups is employed for interface passivation between perovskite and spiro-OMeTAD. We unveil the synergistic mechanism of a) defect-passivation of Pb-related involving coordination and chelation; b) immobilization components through three types of hydrogen bonding interactions; c) enhanced crystallinity and preferential orientation induced by crystal regrowth. These effects minimize the nonradiative recombination and inhibit ion migration. Moreover, TBC introduces a dipole interlayer that facilitates favorable and efficient hole extraction and transport. As a result, the TBC-treated PSCs exhibited a remarkable power conversion efficiency of 24.84%, higher than the control efficiency of 22.04%. Notably, the hydrophobic terminal tert-butyl group confers excellent stability upon the device. Unpackaged devices stored in open-air conditions for 1200 h, experienced only a 5.3% reduction in efficiency. They retained their initial efficiency of 82.7% following 800 h of operation under one-sun illumination in ambient conditions without encapsulation. This proposed interfacial engineering strategy using multiple anchoring groups of amphiphilic molecules presents a new approach for obtaining highly efficient and stable PSCs.

Hierarchical Co3S4 nanostructure coupling with macroporous nickel foam: A robust interfacial solar evaporator for efficient desalination and sustainable freshwater production

Interfacial solar water evaporation (ISWE) technology provides a green, energy-saving and economical way to sustainably produce freshwater from various water sources for addressing the impending water shortage. However, the low evaporation rate, complex manufacturing process and harmful surface salt accumulation for ISWE are still challenging and considerably restricted the practical applications. Herein, we design and fabricate a robust ISWE based on the hierarchical Co3S4 nanostructure as a photothermal absorber and three-dimensional (3D) nickel foam (NF) as a primary structure with macroporous networks. The as-fabricated Co3S4/NF not only introduces sufficient photothermal centers to convert solar energy into heat, but also provides abundant channels for water transportation and steam escape. The Co3S4/NF evaporator exhibits a high evaporation rate of 1.56 kg m−2 h−1 and a photothermal conversion efficiency up to 94.18 % under one-sun illumination. Moreover, such evaporator shows the long-term durability and good salt-resistant ability, which can sustainably produce freshwater from various water sources including seawater, saline water, lake water and other contaminated water. The photothermal Co3S4/NF evaporator would provide a promising platform for the production of drinkable water in a safe and sustainable manner.

Integrated solar evaporator based on photothermal Cu-CuOx/NC with heat-insulated polyurethane foam enabling highly efficient salt-tolerant desalination and water purification

Renewable solar energy meeting photothermal materials provides a promising approach for freshwater production via interfacial steam generation. The design and manufacture of high-performance evaporators are still highly anticipated for practical applications. Herein, the robust and durable solar evaporator is proposed and fabricated by integration of photothermal Cu-CuOx/NC (CNC) and three-dimensional porous structure heat-insulated polyurethane (PU) foam with polyvinyl alcohol (PVA)/sodium alginate (SA) modifications. The designed PVA-SA-CNC/PU simultaneously possesses fast water transmission, broadband light trapping, satisfactory mechanical robustness and effective heat confinement. When applied as a solar evaporator, the PVA-SA-CNC/PU exhibits a high evaporation rate of 1.99 kg m−2 h−1 and operates stably within ten consecutive cycles under one-sun illumination, which can also handle salt tolerant desalination of seawater and saline water to sustainably produce freshwater. In addition, the functional versatility of the fabricated evaporator is explored to purify various wastewater. This study establishes a highly efficient integrated evaporator with multitasking water purification towards the solution of water shortage.

Interfacial Engineering for Efficient Low-Temperature Flexible Perovskite Solar Cells.

Photovoltaic technology with low weight, high specific power in cold environments, and compatibility with flexible fabrication is highly desired for near-space vehicles and polar region applications. Herein, we demonstrate efficient low-temperature flexible perovskite solar cells by improving the interfacial contact between electron-transport layer (ETL) and perovskite layer. We find that the adsorbed oxygen active sites and oxygen vacancies of flexible tin oxide (SnO2) ETL layer can be effectively decreased by incorporating a trace amount of titanium tetrachloride (TiCl4). The effective defects elimination at the interfacial increases the electron mobility of flexible SnO2 layer, regulates band alignment at the perovskite/SnO2 interface, induces larger perovskite crystal growth, and improves charge collection efficiency in a complete solar cell. Correspondingly, the improved interfacial contact transforms into high-performance solar cells under one-sun illumination (AM 1.5G) with efficiencies up to 23.7% at 218 K, which might open up a new era of application of this emerging flexible photovoltaic technology to low-temperature environments such as near-space and polar regions.

Managing Excess Lead Iodide with Functionalized Oxo-graphene Nanosheets for Stable Perovskite Solar Cells.

Stability issues could refrain from commercializing lead halide perovskite solar cells (PSCs) despite having comparable power conversion efficiency (PCE) to silicon solar cells. Overcoming drawbacks affecting their long-term stability is gaining incremental importance. Excess lead iodide (PbI2) causes perovskite degradation, although it aids in crystal growth and defect passivation. Herein, we synthesized functionalized oxo-graphene nanosheets (Dec-oxoG NSs) to effectively manage the excess PbI2. Dec-oxoG NSs provide anchoring sites to bind the excess PbI2 and passivate perovskite grain boundaries, thereby reducing charge recombination loss and significantly boosting the extraction of free electrons. The inclusion of Dec-oxoG NSs leads to a PCE of 23.7% in inverted (p-i-n) PSCs. Devices retain 93.8% of their initial efficiency after 1,000 hours of tracking at maximum power points under continuous one-sun illumination, and exhibit high stability under thermal and ambient conditions.

When Coordination Polymers Meet Wood: From Molecular Design toward Sustainable Solar Desalination.

Solar-driven interfacial evaporation harnessing solar energy on a water surface provides a sustainable and economic means to efficiently capture freshwater from nontraditional water sources. Endowed with a hierarchical porous structure and mechanical stability, wood-based evaporators represent a renewable alternative to petroleum-based materials. Nonetheless, incidental inferiorities of a low evaporation rate and weak interfacial strength are challenging to overcome. Herein, we propose the usage of chemically stable coordination polymers (Ni-dithiooxamidato, Ni-DTA) as hydrophilic photothermal nanomaterials for the molecular design of robust wood-based evaporators with improved performance. In situ synthesis of Ni-DTA onto the channel wall of balsawood provides sufficient photothermal domains that localize the converted energy for facilitated interfacial evaporation. A rational control of methanol/dimethylformamide ratios enables the coexistence of 1D-nanofibers and 0D-nanoparticles, endowing Balsa-NiDTA with a high evaporation rate of 2.75 kg m-2 h-1 and an energy efficiency of 82% under one-sun illumination. Experimental and simulation results reveal that Ni-DTA polymers with strong hydration ability decrease the equivalent evaporation enthalpy induced by decreased H-bonding density of water molecules near the evaporation interface. The Balsa-NiDTA evaporator showed a high chemical stability, mainly due to the robust Ni-S/Ni-N bonds and the superior cellulose affinity of Ni-DTA. Furthermore, the Balsa-NiDTA evaporator shows an excellent antibacterial activity and low oil-fouling propensity. This work presents a facile and mild strategy to design chemically stable wood-based evaporators, contributing to highly efficient and sustainable solar desalination under harsh conditions.

All-perovskite tandem solar cells with 3D/3D bilayer perovskite heterojunction.

All-perovskite tandem solar cells promise higher power-conversion efficiency (PCE) than single-junction perovskite solar cells (PSCs) while maintaining a low fabrication cost1-3. However, their performance is still largely constrained by the subpar performance of mixed lead-tin (Pb-Sn) narrow-bandgap (NBG) perovskite subcells, mainly because of a high trap density on the perovskite film surface4-6. Although heterojunctions with intermixed 2D/3D perovskites could reduce surface recombination, this common strategy induces transport losses and thereby limits device fill factors (FFs)7-9. Here we develop an immiscible 3D/3D bilayer perovskite heterojunction (PHJ) with type II band structure at the Pb-Sn perovskite-electron-transport layer (ETL) interface to suppress the interfacial non-radiative recombination and facilitate charge extraction. The bilayer PHJ is formed by depositing a layer of lead-halide wide-bandgap (WBG) perovskite on top of the mixed Pb-Sn NBG perovskite through a hybrid evaporation-solution-processing method. This heterostructure allows us to increase the PCE of Pb-Sn PSCs having a 1.2-µm-thick absorber to 23.8%, together with a high open-circuit voltage (Voc) of 0.873 V and a high FF of 82.6%. We thereby demonstrate a record-high PCE of 28.5% (certified 28.0%) in all-perovskite tandem solar cells. The encapsulated tandem devices retain more than 90% of their initial performance after 600 h of continuous operation under simulated one-sun illumination.

Scalable Core–Sheath Yarn for Boosting Solar Interfacial Desalination Through Engineering Controllable Water Supply

Tailoring water supply to achieve confined heating has proven to be an effective strategy for boosting solar interfacial evaporation rates. However, because of salt clogging during desalination, a critical point of constriction occurs when controlling the water rate for confined heating. In this study, we demonstrate a facile and scalable weaving technique for fabricating core–sheath photothermal yarns that facilitate controlled water supply for stable and efficient interfacial solar desalination. The core–sheath yarn comprises modal fibers as the core and carbon fibers as the sheaths. Because of the core–sheath design, remarkable liquid pumping can be enabled in the carbon fiber bundle of the dispersed super-hydrophilic modal fibers. Our woven fabrics absorb a high proportion (92%) of the electromagnetic radiation in the solar spectrum because of the weaving structure and the carbon fiber sheath. Under one-sun (1 kW·m−2) illumination, our woven fabric device can achieve the highest evaporation rate (of 2.12 kg·m−2·h−1 with energy conversion efficiency: 93.7%) by regulating the number of core–sheath yarns. Practical application tests demonstrate that our device can maintain high and stable desalination performance in a 5 wt% NaCl solution.

Hydrazonothiazole dyes for enhanced dye-sensitized solar cells in greenhouse applications: Achieving high power conversion efficiency and long-term stability

Dye-sensitized solar cells (DSSCs) offer a cost-effective and attractive alternative to traditional solar cells for greenhouse applications. Hydrazonothiazole dyes (MHS-1-4) have been investigated as a viable DSSC technology, with researchers designing dyes that absorb light in the green region, while transmitting light in the red and blue regions, making them the ideal fit for plant growth. Sensitized devices display impressive power conversion efficiency (PCEs) ranging from 6.27 to 8.85%, with MHS-4 DSSCs achieving an 8.85% power conversion efficiency, a short-circuit photocurrent density of 17.90 mA cm−2, and a maximum incident monochromatic photon-to-electron conversion efficiency (IPCE) of 80%. Furthermore, DSSCs based on MHS-4 demonstrate excellent long-term stability, sustaining nearly constant power conversion efficiency after exposure to one-sun illumination for 1000 h. This breakthrough study demonstrates the potential for hydrazonothiazole dyes in DSSCs, marking a significant step forward in the development of cost-effective solar cell technology compatible with plant growth. With MHS-1-4 dyes' ability to effectively convert photoelectric energy throughout the visible range, and even into the near-infrared (NIR) region up to 900 nm, they offer a new benchmark for DSSC technology.

A solar-driven seawater desalination and electricity generation integrating system based on carbon black-decorated magnetic phase-change composites

We have developed a novel type of solar-driven interfacial evaporation and electricity generation integrating system based on the modified carbon black (MCB)-decorated magnetic phase-change composites (MCB-MPCC) for continuous seawater desalination and clean electric power generation under intermittent solar illumination. In this system, MCB-MPCC acts as not only a solar absorber but also a hydrovoltaic functional coating. MCB-MPCC was fabricated through encapsulating n-docosane as a phase change material (PCM) in a SiO2/Fe3O4 composite shell through emulsion-templated interfacial polycondensation, followed by coating a polydopamine layer and surface-depositing MCB nanoparticles. Owing to the introduction of a PCM core, the resultant MCB-MPCC obtained a high latent heat capacity of over 145 J g−1 for consecutive seawater evaporation under intermittent solar illumination. Moreover, the surface-decorated MCB nanoparticles contribute to superior sunlight absorptivity and good wettability of MCB-MPCC, promoting a high evaporation rate of 2.67 kg m−2 h−1 for the MCB-MPCC-based evaporator under one-sun illumination along with excellent salt resistance. Meanwhile, the developed system achieved a stable output voltage of 0.43 V and output current of 10.05 μA under one-sun illumination, and the generated electric power could be stored by a commercial capacitor to provide a power supply for lightening an LED lamp.

Stabilization of FAPbI3 with multifunctional alkali-functionalized polymer.

The defects located at the interfaces and grain boundaries (GBs) of perovskite films are detrimental to the photovoltaic performance and stability of perovskite solar cells. Manipulating the perovskite crystallization process and tailoring the interfaces with molecular passivators are mainly effective strategies to mitigate performance loss and instability. Herein we report a new strategy to manipulate the crystallization process of FAPbI3 -rich perovskite by incorporating a small amount of alkali functionalized polymers into the antisolvent solution. The synergic effects of alkali cations and polyacrylic acid anion effectively passivate the defects on the surface and GBs of perovskite films. As a result, the rubidium (Rb)-functionalized polyacrylic acid significantly improves the power conversion efficiency of FAPbI3 perovskite solar cells to approaching 25% and reduces the risk of lead ion (Pb2+ ) leakage via the strong interaction between C = O bond and Pb2+ . In addition, the unencapsulated device shows enhanced operational stability, retaining 80% of its initial efficiency after 500h operation at maximum power point under one-sun illumination. This article is protected by copyright. All rights reserved.

Quenching Detrimental Reactions and Boosting Hole Extraction via Multifunctional NiOx /Perovskite Interface Passivation for Efficient and Stable Inverted Solar Cells.

Nickel oxide (NiOx ) is one of the most promising hole transport materials for inverted perovskite solar cells (PSCs). However, its application is severely restrained due to unfavorable interfacial reactions and insufficient charge carrier extraction. Herein, a multifunctional modification at the NiOx /perovskite interface is developed via introducing fluorinated ammonium salt ligand to synthetically solve the obstacles. Specifically, the interface modification can chemically convert detrimental Ni≥3+ to lower oxidation state, resulting in the elimination of interfacial redox reactions. Meanwhile, interfacial dipole is incorporated simultaneously to tune the work function of NiOx and optimize energy level alignment, which effectively promotes the charge carrier extraction. Therefore, the modified NiOx -based inverted PSCs achieve a remarkable power conversion efficiency (PCE) of 22.93%. Moreover, the unencapsulated devices obtain a significantly enhanced long-term stability, maintaining over 85% and 80% of the initial PCEs after storage in ambient air with a high relative humidity of 50-60% for 1000h and continuous operation at maximum power point under one-sun illumination for 700h, respectively.

Controlled crystallization and surface engineering of mixed-halide γ-CsPbI2Br inorganic perovskites via guanidinium iodide additive in air-processed perovskite solar cells

In this report, we demonstrate enlarged grain size (up to ∼3 μm) in ambient-stable black γ-phase CsPbI2Br thin films through the regulated addition of guanidinium iodide (GAI) as an effective volatile additive. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) measurements indicate the complete sublimation of GAI following annealing, with no inclusion inside the final γ-CsPbI2Br perovskite lattice. GAI is found to participate by retarding the cation–anion reaction via the Cs+ and GA+ cation-exchange process. We find that inorganic perovskite solar cells (IPSCs) devices made from (CsPbI2Br)0.925 + 0.075 GAI and a phenyltrimethylammonium chloride (PTACl) passivation retain a solar-friendly band-gap of 1.91 eV and excellent device performance, with the best open-circuit voltage reaching as high as 1.34 V, with highly reproducible and stable photo conversion efficiencies of 16.88% (for 0.09 cm2) and 15.60% (large area 1 cm2) under ambient conditions. Photostability analysis further demonstrated negligible efficiency loss over 1000 h under continuous one-sun equivalent illumination, indicating GAI additive as a promising approach toward ambient stable, all-inorganic high-efficiency solar cells.

Nanostructured Semiconductor Photoelectrodes Complexed with Natural Photosystems I and II for Bias-Free Tandem Biophotovoltaics

Natural photosynthesis can offer attractive models for light-harvesting antennae, electron- and proton-transfer units, and catalytic clusters for photovoltaics and solar fuel production. However, photoelectrodes with natural photosystems exhibit relatively low performances due to poor interfacial electron transfer. Here, we present efficient bias-free biophotovoltaics (BPVs) based on dual heterostructure photoelectrodes comprising natural photosystems and semiconductor nanostructures. The photocathode and photoanode were prepared using photosystem I (PSI)-protonated carbon nitride (p-C3N4) nanosheet complexes and a photosystem II (PSII)–TiO2 nanoparticle film, respectively. The linker-free complexation of PSI and PSII with nanostructured semiconductors efficiently suppressed the recombination of photogenerated charges for efficient light harvesting and photoconversion. In particular, the oriented coupling of the negatively charged luminal side of PSI to protonated carbon nitride synergistically increased the photoelectron generation and charge transfer, resulting in the generation of a photocurrent density 28 times higher than that of randomly oriented PSI. Under one-sun simulated illumination, the BPV cell with the PSI-p-C3N4 and PSII–TiO2 tandem structure exhibited a photocurrent of 7.7 μA cm–2 without any external bias and a cell power up to 0.9 μW cm–2. This work provides a simple self-assembly method to construct efficient nanobio complex photoelectrodes based on natural photosystems coupled with semiconductor nanostructures in a favorable orientation for efficient and stable interfacial electron transfer.