Solar RRL

Hygroscopicity risk and organic–inorganic hybrid perovskites easy decomposition in solar cells limit their usefulness. Apart from the hybrid organic–inorganic perovskites, inorganic perovskite solar cells display a better stability toward moisture, light soaking, and thermal stressing. However, most inorganic perovskites are inappropriate for single junction or tandem solar cells due to their large bandgaps (>1.8 eV), which eventually results in light absorption loss. Fortunately, cubic CsPbI₃ perovskite (having 1.73 eV bandgap) could potentially serve as top cells in tandem devices with silicon solar cells. Poor phase stability of CsPbI₃ is considered a major obstacle to design CsPbI₃ perovskite solar cells. This review highlights the most recent studies on the progress in CsPbI₃‐based solar cell device field. Moreover, this review also summarizes certain strategies to improve phase stability, such as size reduction to nanocrystal or external cations/anions doping, with the aim to improve the devices design.

Photocatalytic CO₂ reduction to value‐added fuels is an appealing avenue in response to global warming and the energy crisis, but it still suffers from high energy barriers, low conversion efficiencies, and poor photostability. Herein, a novel S‐scheme SnNb₂O₆/CdSe–diethylenetriamine (SNO/CdSe–DET) heterojunction is designed by a microwave‐assisted solvothermal process, composed of 2D ultrathin SNO nanosheets (NSs) and amine‐modified CdSe–DET nanorods (NRs). The SNO/CdSe–DET composite without any co‐catalyst possesses a boosted performance in the solar‐driven photocatalytic conversion of CO₂ to CO, and the highest CO evolution rate achieved is 36.16 μmol g⁻¹ h⁻¹, which is roughly 3.58 and 9.39 times greater than those of CdSe–DET and SNO under visible‐light illumination. Such a superior activity should be ascribed to the S‐scheme system, which benefits the separation of the photogenerated carriers and promotes the synergy between CdSe–DET NRs and SNO NSs by strong chemical‐bonding coordination. Meanwhile, DET can enhance CO₂ adsorption/activation and precisely regulate the surface reactive sites. This innovative work provides fresh insight into the development of highly efficient S‐scheme photocatalytic heterostructures for CO₂ reduction.

Solar steam generation offers a sustainable strategy to mitigate global clean water scarcity. To this end, 3D photothermal evaporators have attracted increasing research interest since they can significantly improve both evaporation rate and energy efficiency. However, compared to the 2D evaporators, the 3D ones consume more raw materials and occupy more storage space, which limits their applications for practical portable solar steam generation. To address this issue, a 3D hollow and compressible photothermal evaporator is designed and fabricated which can be compressed to less than one third of its original volume, thus enabling easier transport and storage. Moreover, under 1.0 sun illumination, all evaporation surfaces of this 3D evaporator are lower in temperatures than the surrounding environment, thus providing the unique advantage of zero energy loss to the environment during solar evaporation. Due to the all‐cold evaporation surfaces, during solar evaporation, the evaporator is able to harvest massive energy from both the surrounding air and bulk water, delivering an extremely high evaporation rate of up to 7.6 kg m⁻² h⁻¹ under 1.0 sun irradiation. Furthermore, seawater desalination tests demonstrate that the device has great potential for portable solar thermal desalination by delivering clean water with a salinity well below 50 ppb.

An ideal crystal quality in the grain interior of perovskite polycrystalline films is well recognized; therefore, understanding interfacial impact and the ways to limit interfacial recombination is critical to fabricating highly efficient solar cells. In perovskite solar cells, PbI₂ has been used to passivate defects at grain boundaries, yet a systematic PbI₂ passivation engineering to boost the high‐performance perovskite solar cells has not been fully explored. Here, a novel device structure comprised of double‐side‐passivated perovskite solar cells (DSPC) is devised through intentionally distributing PbI₂ to both the front/rear‐side surfaces and grain boundaries of the formamidinium‐lead‐iodide‐based (FAPbI₃‐based) perovskite film. The minority carrier lifetime in double‐side‐passivated perovskite is extended to 1.1 μs with single‐exponential decay using time‐resolved photoluminescence. This result indicates a generic passivation effect of PbI₂ on perovskite interfaces, resembling SiO₂ passivation in silicon solar cells. Correspondingly, the best photovoltaic device with TiO₂‐based planar structure presents a stabilized efficiency of 22%. Moreover, DSPC effectively boosts the limits of open circuit voltages toward a record potential loss of 0.38 V for 1.53 eV‐bandgap perovskites. The architecture of double‐side‐passivated perovskite opens up new opportunities to exceed the efficiency of state‐of‐the‐art perovskite solar cells.

An efficient full solar spectrum ultraviolet–visible–near infrared (UV–vis–NIR) light‐driven Cu_2–xS/g‐C₃N₄ composite photocatalyst is reported, which is fabricated by a facile solvothermal process for CO₂ photoreduction into CO and CH₄, as confirmed by product analysis and ¹³C isotopic test. The composite exhibits superior full solar‐spectrum‐driven CO₂ photoreduction performance than pure Cu_2–xS and g‐C₃N₄, which is attributed to the efficient charge transfer due to the formation of intimate interface contact and SC bond coupling between Cu_2–xS and g‐C₃N₄ based on experimental analyses and theoretical calculations. In particular, the activities of the best composite for CO₂ photoreduction into CO and CH₄ under NIR light irradiation are about 2.6 times and 6.6 times higher than that of Cu_2–xS, whereas no production is measured over g‐C₃N₄. A possible mechanism of photocatalytic CO₂ reduction is given based on in situ Fourier transform infrared (FTIR) analysis. This study paves the way to prepare carbon nitride–based photocatalysts with full‐spectrum‐responsive property for efficient CO₂ photoreduction.

Control of dynamics at the electron transport layer–perovskite interface, such as charge transfer and recombination, is essential in achieving high‐efficiency planar perovskite solar cells (PSCs). Herein, it was observed that the trade‐off between unfavorable electron transport of a thick SnO₂ film and serious electron recombination at thin SnO₂ film/perovskite interfaces is essential for the performance of SnO₂‐based planar PSCs. The optimized efficiency of devices beyond 20% is obtained by using a two‐step deposition of SnO₂. Moreover, trap‐assisted carrier recombination is significantly suppressed by using the diethylenetriaminepentaacetic acid passivator via the formation of coordination with undercoordinated Sn and Pb²⁺ ions. As a result, the champion device demonstrates a promising efficiency of 21.28% with negligible hysteresis and much improved environmental stability, i.e., retaining 98% of the initial efficiency under ambient atmosphere over 1000 h.

Czochralski‐grown gallium‐doped silicon wafers are now a mainstream substrate for commercial passivated emitter and rear cell (PERC) devices and allow retention of established processes while offering enhanced cell stability. We have assessed the carrier lifetime potential of such Czochralski‐grown wafers in dependence of resistivity, finding effective lifetimes well into the millisecond region without any gettering or hydrogenation processing, thus demonstrating one advantage over boron‐doped silicon. Second, the stability of gallium‐doped PERC cells are monitored under illumination (>3000 h in some cases) and anomalous behavior is detected. While some cells are stable, others exhibit a degradation then recovery, reminiscent of light and elevated temperature‐induced degradation (LeTID) observed in other silicon materials. Surprisingly, cells from one ingot exhibit LeTID‐like behavior when annealed at 300 °C but near stability when not annealed, but, for another ingot, the opposite is observed. Moreover, a stabilization process typically used to mitigate boron–oxygen degradation does not influence any cells that are studied. Secondary‐ion mass spectrometry of the PERC cells reveals significant concentrations of unintentionally incorporated boron in some cases. Nevertheless, even in the absence of mitigating light‐induced degradation, Ga‐doped silicon is still more stable than unstabilized B‐doped silicon under illumination.

Over the years, researchers have placed increasing focus on extending the application of photocatalytic hydrogen (H₂) evolution to seawater. Herein, a photocatalytic system with a unique combination of P‐doped Zn_0.5Cd_0.5S (pZCS) and noble‐metal‐free CoP is first fabricated to evaluate the synergy between them. The resultant sample achieves a significantly boosted photocatalytic H₂ evolution reaction (HER) with a rate of 5488.8 μmol g⁻¹ h⁻¹, which is an almost 50‐fold enhancement from its pristine ZCS counterpart. Impressively, the CoP–pZCS composite also demonstrates overall water splitting where no sacrificial reagent is used, with an H₂ evolution rate of 154.6 μmol g⁻¹ h⁻¹. The sample is then tested for its HER activity in seawater, and 3956.0 μmol g⁻¹ h⁻¹ of H₂ is acquired. The main factor that contributes to its high performance in seawater despite various distractions coming from the abundance of ions present is the synergistic relation between pZCS and CoP. The midgap state procured through the introduction of the P dopant has excellent electron–hole separating ability, and CoP further serves as an electron sink where the photogenerated electrons can rapidly assemble. Ultimately, the charge carrier recombination within the resultant composite is greatly hindered, thus a spectacular photocatalytic HER in seawater is enabled.

To achieve efficient organic solar cells (OSCs), the design of promising non‐fullerene small molecular acceptors (SMAs) is crucially important and the relationship between the chemical structure and optoelectronic properties needs to be further investigated. Herein, an A₂‐A₁‐D‐A₁‐A₂ molecular skeleton is adopted to study the effect of end‐capped A₂ groups containing different numbers of cyano units, where D and A₁ are fixed as indacenodithiophene (IDT) and benzotriazole (BTA) units, respectively. Utilizing the “same‐acceptor‐strategy,” three BTA‐based SMAs, named as BTA701, BTA3, and BTA703, are paired with a BTA‐based p‐type polymer J71. The open‐circuit voltage (V_OC) gradually decreases with the enhancement of electron‐accepting ability of terminal A₂ units, from 1.32 V (BTA701) to 1.20 V (BTA3) and to 0.85 V (BTA703). The device J71:BTA3 eventually shows the best power conversion efficiency (PCE) of 8.60% with a V_OC up to 1.2 V because of the complementary light absorption, high and balanced hole and electron mobility, suitable phase separation, and crystallinity. This study indicates that appropriate cyano‐containing units in BTA‐based SMAs can effectively modulate the absorption, energy levels, charge mobility and surface free energy, which can provide valuable insights to the further design of SMAs. In addition, these results prove that the “same‐acceptor‐strategy” is simple and effective to realize a V_OC as high as 1.2V.

Electron transport materials (ETMs) are considered a keystone component of third‐generation solar cells. Among the alternative ETM, metal oxide bilayers have attracted increasing attention due to their easy processing and tunability of cascade energy alignment. Herein, a metal oxide bilayer that combines ZnO and TiO₂ compact films (ZnO/TiO₂) is implemented as ETM for solution‐processed Sb₂S₃ planar solar cells. The bilayer ETM achieves the highest photovoltaic performance when compared with devices based on single ETM. Thus, the optimized device based on ZnO/TiO₂ ETM yields a champion efficiency of 5.08% with an open‐circuit voltage of 0.58 V and a current density of 16.17 mA cm⁻². Using surface photovoltage, electrochemical impedance spectroscopy, and current density–voltage analyses, it is demonstrated that the use of ZnO/TiO₂ promotes charge injection, decreases series resistance and shutting paths, and leads to the reduction of charge recombination at the ETM/Sb₂S₃ interface.