Tandem Solar Cells

In article number 2100781, Wenzhong Shen and co-workers have proposed and proven that bifacial perovskite/c-Si tandem solar cells can not only improve the energy output, but also significantly reduce the Si thickness while maintaining the high efficiency. The photovoltaic performance of bifacial perovskite/c-Si tandem solar cells combining existing large-scale preparation technologies, was also optimized.

Volume Photocatalysis

In article number 2100823, Yuexiang Li and co-workers found that tube-like polymeric carbon nitride with wall nanopores which was prepared by pyrolyzing needle-like urea, shows enhanced photoabsorption under strong irradiation, and allows the reactant formic acid to effectively insert into its volume/interlayers. Different from conventional surface photocatalysis, the reaction efficiency of the volume photocatalysis rises with irradiation intensity.

Perovskite Solar Cells

In article number 2100671, Yu-Ching Huang and co-workers developed a process for fabricating perovskite solar cells with all-oxide charge transporting layers under ambient condition. By using solid-state ligand exchange at room temperature, the more conductive Ta-doped SnO₂ could be applied to manufacture perovskite solar cells with excellent operation stability.

The optoelectronic properties and potential of Cs₂AgBiBr₆ double perovskites with respect to their application in lead-free perovskite solar cells are discussed.

This Perspective highlights a wide variety of metal chalcohalide semiconductors relevant for photovoltaic applications. These rather overlooked materials present a high degree of bandgap tunability which makes them suitable as single-junction solar cell absorbers as well as low- or wide-bandgap light-harvesting materials in multijunction configurations. Furthermore, many metal chalcohalides are based on relatively abundant and low-toxicity elements.

Ternary organic solar cells (OSCs) are high-performance solar cells based on photovoltaic technologies that have emerged as potential energy technologies. The active layers of ternary OSCs comprise donor/acceptor host components and a third component. This review categorizes and describes the effects that the role and function of the third component have on the efficiency and stability of ternary OSCs.

The past decade has witnessed the rapid growth of 2D MXenes; they have shown flexible optical properties, strong localized surface plasmon resonance mechanism, and special response to light in solar water desalination. Herein, the main strategies for constructing MXenes-based photothermal evaporators for efficient desalination are highlighted. The key challenges are also discussed and future directions of this hot topic are outlined.

Structural and theoretical aspects of ABO₃ perovskites along with its photovoltaic performances aid to develop better photoanodes for dye-sensitized solar cells.

A quite thick c-Si bottom-cell has to be used to fully absorb near-infrared photons, which greatly improves the cost of the perovskite/c-Si tandem solar cells (TSCs). The bifacial two-terminal TSCs can not only improve the energy output, but also significantly reduce the Si thickness while maintaining high efficiency.

Hierarchically porous U-PCN-480 prepared by template-free pyrolysis of urea is a volume photocatalyst (VPt). Its porous structure enhances the photoabsorption under strong irradiation. The VPt displays excellent volume photocatalysis (VPs) activity for hydrogen evolution in the formic acid reaction system. Notably, the reaction efficiency increases with increasing irradiation intensity due to the synergy between VPs and the enhanced photoabsorption.

A room temperature solid-state ligand exchange method modified tantalum-doped tin oxide (Ta-SnO₂) with a functional ligand, enhancing the conductivity of Ta-SnO₂ and improving the band alignment with the electrode is reported. Furthermore, the efficiency of fullerene-free devices can achieve up to 15.48%. All-oxide devices can maintain 80% performance after 1000 and 540 h under damp heat and light soaking tests.

The resistance of perovskite solar cells (PSC) to potential induced degradation (PID) is investigated by the help of I–V curve, electroluminescence, external quantum efficiency measurements, and secondary ion mass spectrometry. The PSCs are PID proof when they are exposed to current system voltages but degrade very fast if they are exposed to a high voltage of −1000 V.

Phenyl extended naphthalene-based-covalent triazine frameworks (PhN-CTFs) result in effective heterogeneous photocatalysts for the metal-free selective aerobic oxidation of sulfides to sulfoxides and the cross-dehydrogenative C—C coupling reaction under visible-blue light irradiation. The PhN-CTFs also exhibited good substrates applicability for both reactions as well as excellent chemical stability.

The process called high vapor transport deposition is applied for the first time to deposit kesterite absorber films. The main advantage of this process is the fine tuning capabilities to control the desired stoichiometry in the absorber layer. Additionally, the process allows a high deposition rate and low temperature in the evaporation cells where raw materials are placed.

The planarity of two new small-molecule acceptors, based on diketopyrrolopyrrole, is achieved by noncovalent intramolecular interactions. These molecules show broad absorption in the visible and near-infrared region. Binary solar cells built together with a polymer display power conversion efficiency as high as 14.12%.

Strategies to mitigate the influence of interfacial recombination in Sb₂Se₃/CdS solar cells are investigated. The surface sulfurization of the absorber allows to lower the valence band at the vicinity of the pn junction and repels the photoholes from the space charge region, thus quenching interface recombination and significantly improving the power conversion.

Hydrothermal-synthesized Cu-doped Ga₂O₃ nanocrystals are used as the hole transport material of inverted perovskite solar cells. Cu dopants remarkably improve the performance of devices, which is related to the additional hole transport channels from impurity levels.

For the first time, it is demonstrated that an organic solar cell (OSC) using the Dawson-type polyoxometalate as hole collection material can exhibit superior photovoltaic efficiency to the device modified by classic interlayer PEDOT:PSS. The results herein suggest that the Dawson-type polyoxometalates can be used as low-cost and effective anode interlayers for the future manufacturing of OSCs.

A power-conversion efficiency of 2.51% with short-circuit current density of 28.07 mA cm⁻² is realized for the thin-film solar cell fabricated using a vapor-transport-deposited orthorhombic tin-selenide absorber layer.

The Ti₃C₂T_X MXene surface activated by diaminoethanethiol molecules has a tuned work function and couples with Cd_0.4Zn_0.6S to form Schottky junctions. The built-in electric field formed by the surface charge rearrangement is more favorable for the rapid transfer of photogenerated electrons, which makes it exhibit an excellent photocatalytic hydrogen evolution performance.

Incorporation of the pseudo-alkali metal cation dimethylammonium into the Cs-stabilized formamidinium lead triiodide perovskite precursor solution for fabricating the printed perovskite solar cells, achieves crystallization control and grain boundary passivation of the perovskite in the mesoscopic scaffold, yielding a device with a power conversion efficiency of 17.46% and long-term operational stability.

An innovative quasi-interdigitated back-contact (QIBC) perovskite solar cell (PSC) structure featuring a front-carrier transport layer (FCTL) and a broad back-contact pitch is reported. The optimized QIBC-PSC with CuO FCTL demonstrates the best-modeled efficiency of 23.23%, with over 25% efficiency available.

In directly coupled photovoltaic (PV)-assisted water splitting systems, the limit of solar-to-hydrogen efficiency (STH) can be predicted using polarization curves of the electrochemical (EC) cells even without analysis of the PV current–voltage characteristics. The method to find points of optimal coupling between PV and EC, STH limit, and effect of the EC/PV active area ratio are presented.

Eight types of halide perovksites are trained through a generative machine learning approach for solar cells’ fabrication and the random forest model prediction of the bandgap and performance with the experimental results is validated.

A general method is proposed for extracting the specific contact resistance of a transition metal oxide/a-Si:H(i)/c-Si(n) heterojunction. A deeper theory of ρ_C extraction is revealed after comprehensive understanding of the transport mechanism at dopant-free heterojunctions (DFHJs). A double (diode + resistance) model is implemented to quickly extract and fit the key parameters of DFHJs.

The slot-die coating cycle in ambient conditions is developed for inverted perovskite mini-modules based on MAPbI₃ and CsFAPbI₃ absorbers. The use of Cl-additives in combination with vacuum quenching is found to be essential for crystallization and uniform morphology of perovskite films and charge transporting layers. Slot-die fabrication was successfully upscaled for mini-modules which demonstrated up to 14.9% of power conversion efficiency.

One-photon excitation pathway-based heterostructure design is emerging as an effective approach to promote the visible-light photocatalysis of C₃N₄. Herein, the counter-intuitive phenomenon is provided that a low crystalline electron acceptor is favorable for constructing a highly efficient interface and thus achieving superior photocatalytic activity under visible light.

Thin film solar cells based on high bandgap Cu₂ZnGeS₄ absorbers are fabricated with alternative Zn_{1– x} Sn _x O _y buffer layers using atomic layer deposition. High open-circuit voltage of up to 1.1 V is obtained, but short-circuit current is limited. Etching of the absorber, with likely removal of germanium oxide influences both current and voltage and large room for further improvements is envisaged.

Herein, a scalable and high-performance silver electrode that can serve as a printable replacement to evaporated silver electrodes commonly used in literature is presented. Devices with newly developed electrodes achieve almost the same power conversion efficiencies as evaporated ones. Higher shunt resistances than their vacuum counterparts are also observed and thus perform significantly better under low light conditions.

Hierarchical photothermal hydrogel evaporator, prepared by solar-initiated frontal polymerization strategy, featuring broadband optical absorption and high swelling ratio enables enhanced solar water evaporation via low evaporation enthalpy and greatly enlarged evaporation surface area and volume, which provides an alternative opportunity for on-site freshwater production for remote areas/emergency needs.

Microwave irradiation allows a quick low-temperature crystallization of nickel oxide within minutes. Moreover, the doping of In and Sn metal ions diffused from the indium tin oxide layer takes place, leading to unique chemical compositions. The perovskite solar cells with the microwave-annealed nickel oxides show better photovoltaic performances.

Photoelectrochemical water splitting to hydrogen is a clean process that can achieve green hydrogen. Herein, highly efficient unassisted solar water-splitting devices based on perovskite/silicon tandem solar cells protected by high-transmittance and chemical stability quartz glass are presented, which exhibit a solar–to-hydrogen efficiency of 19.68%.

Herein, a new strategy based on intermediate engineering is reported for the preparation of high-quality, wide-bandgap, mixed-cation lead mixed-halide perovskite FA_0.83Cs_0.17PbI_1.8Br_1.2. The phase-pure intermediate is crystallized at a high crystalline level, which facilitates the subsequent crystallization of high-quality perovskite thin films and therefore, results in enhanced device performance.

A trifluoroethoxyl functionalized hole transport material, Spiro-4TFETAD, is designed and synthesized. Spiro-4TFETAD shows lower highest occupied molecular orbital level, improved hole mobility, conductivity, and hydrophobicity, as well as effectiveness in minimizing perovskite decomposition, compared to Spiro-OMeTAD. Spiro-4TFETAD-based perovskite solar cells exhibit a power conversion efficiency up to 21.11% with excellent stability, which are superior to those of Spiro-OMeTAD-based devices.

A 24 h uninterrupted self-generation power device based on the radiative cooling emitter and the selective solar absorber (SSA) is fabricated. Maximum output powers of 695.1 mW m⁻² in clear daytime and 5.23 mW m⁻² in clear nighttime are obtained. The addition of SSA greatly increases the temperature difference and the average work temperature of the device, which brings higher output power.

For the first time, a certified fill factor value of 79% is obtained for hole selective layer-free carbon-based perovskite solar devices. The influence of charge recombination and transport losses is assessed. An optimized saturated vapor crystallization in the mesoscopic stack allows for minimized losses, leading to a better interface formation between the perovskite and the adjacent interfaces.

Herein, two spirobifluorene-based dyes are deposited from aqueous solutions as efficient anode interlayers (AILs) as a step towards all-solution-processed environmentally friendly organic solar cells. The nonacidic nature of these water-soluble small molecules solves the electrode corrosion issue associated with the commonly employed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) interlayers while producing higher efficiencies than the photovoltaic devices prepared with PEDOT:PSS AILs.

Herein, photothermal materials by cohydrothermal carbonization of cotton stalks and MnO₂ are prepared. They have excellent photothermal performance, evaporation efficiency up to 2.43 kg m⁻² h⁻¹, with outstanding stability. Carbon dots (CDs) are found through cycling of hydrothermal carbonization fluid. CDs and MnO₂ act synergistically to improve the evaporation efficiency of the material up to 2.85 kg m⁻² h⁻¹.