lizhendong

Semitransparent perovskite solar cells based on smooth perovskite films and ultrathin Cu (1 nm)/Au (7 nm) metal electrode demonstrate an efficiency of 16.5%. When illuminated through the semitransparent perovskite cell, a near-infrared-enhanced silicon heterojunction solar cell operates with 6.5% efficiency, leading to a total perovskite/silicon four-terminal tandem efficiency of 23.0%.

Molecular hydrogen can be generated renewably by water splitting with an “artificial-leaf device”, which essentially comprises two electrocatalyst electrodes immersed in water and powered by photovoltaics. Ideally, this device should operate efficiently and be fabricated with cost-efficient means using earth-abundant materials. Here, a lightweight electrocatalyst electrode, comprising large surface-area NiCo₂O₄ nanorods that are firmly anchored onto a carbon–paper current collector via a dense network of nitrogen-doped carbon nanotubes is presented. This electrocatalyst electrode is bifunctional in that it can efficiently operate as both anode and cathode in the same alkaline solution, as quantified by a delivered current density of 10 mA cm⁻² at an overpotential of 400 mV for each of the oxygen and hydrogen evolution reactions. By driving two such identical electrodes with a solution-processed thin-film perovskite photovoltaic assembly, a wired artificial-leaf device is obtained that features a Faradaic H₂ evolution efficiency of 100%, and a solar-to-hydrogen conversion efficiency of 6.2%. A detailed cost analysis is presented, which implies that the material-payback time of this device is of the order of 100 days.

An artificial-leaf device is constructed by driving two carbon-based, bifunctional, and lightweight catalyst electrodes immersed in water with an assembly of solution-processed perovskite photovoltaics. The device delivers hydrogen gas at 100% Faradaic efficiency and with a solar-to-hydrogen efficiency of 6.2%, and a cost analysis suggests that the material-payback time can be of the order of 100 days.

T. P. Russell, R. Zhu, and co-workers present on page 4822 the patterning of silver nanowire transparent electrode by a neutral vapor etching process. Multi-length-scaled silver nanowire grids are demonstrated as the transparent conducting electrodes for polymer solar cells. Improved optical transmittance and enhanced usage of incident photons are achieved.

Multifunctional energy storage and conversion devices that incorporate novel features and functions in intelligent and interactive modes, represent a radical advance in consumer products, such as wearable electronics, healthcare devices, artificial intelligence, electric vehicles, smart household, and space satellites, etc. Here, smart energy devices are defined to be energy devices that are responsive to changes in configurational integrity, voltage, mechanical deformation, light, and temperature, called self-healability, electrochromism, shape memory, photodetection, and thermal responsivity. Advisable materials, device designs, and performances are crucial for the development of energy electronics endowed with these smart functions. Integrating these smart functions in energy storage and conversion devices gives rise to great challenges from the viewpoint of both understanding the fundamental mechanisms and practical implementation. Current state-of-art examples of these smart multifunctional energy devices, pertinent to materials, fabrication strategies, and performances, are highlighted. In addition, current challenges and potential solutions from materials synthesis to device performances are discussed. Finally, some important directions in this fast developing field are considered to further expand their application.

Multifunctional energy storage and conversion devices incorporate novel features and functions in intelligent and interactive modes. Advisable materials, device designs, and performances are reviewed in terms of energy electronics endowed with smart functions like self-healability, electrochromism, shape memory, photodetection, and thermal responsivity. The current challenges, potential solutions, and future directions are discussed to further expand their application and deepen understanding.

This study presents new hole-transport materials (HTMs) to replace the central spiro linkage in spiro-OMeTAD by a CC bond in H11 and CC double bond in H12. This structural change results in a facile synthetic process and a significant change in the molecular geometry. Employing H11 as HTM in combination with mixed ion perovskite [HC(NH₂)₂]_0.85(CH₃NH₃)_0.15Pb(I_0.85Br_0.15)₃, gives a solar cell power conversion efficiency of 19.8%.

On page 4653, N. Zhao, M. A. Loi, and co-workers report a giant light-induced enhancement of the photoluminescence intensity in formamidinium lead iodide perovskite thin films. They demonstrate that the “brightening” of the perovskite can be attributed to a moisture-assisted light-healing effect, which can be potentially used to increase and control the quality of hybrid perovskite thin films.

Highly efficient electron extraction is achieved by using a photoconductive cathode interlayer in inverted ternary organic solar cells (OSCs) where a near-IR absorbing porphyrin molecule is used as the sensitizer. The OSCs show improved device performance when the ratio of the two donors varies in a large region and a maximum power conversion efficiency up to 11.03% is demonstrated.

Uniform perovskite films are achieved by HCl-assisted one-step spin-coating at room temperature. By this method, a highest power conversion efficiency of 17.9% is obtained for perovskite solar cells (PSCs). The devices retain ≈95% of their original efficiency after storage in air for two months. The highest efficiency obtained for large-area PSCs (0.86 cm²) is 15.7%.

Solution-processed few-layer MoS₂ flakes are exploited as an active buffer layer in hybrid lead–halide perovskite solar cells (PSCs). Glass/FTO/compact-TiO₂/mesoporous-TiO₂/CH₃NH₃PbI₃/MoS₂/Spiro-OMeTAD/Au solar cells are realized with the MoS₂ flakes having a twofold function, acting both as a protective layer, by preventing the formation of shunt contacts between the perovskite and the Au electrode, and as a hole transport layer from the perovskite to the Spiro-OMeTAD. As prepared PSC demonstrates a power conversion efficiency (η) of 13.3%, along with a higher lifetime stability over 550 h with respect to reference PSC without MoS₂ (Δη/η = −7% vs. Δη/η = −34%). Large-area PSCs (1.05 cm² active area) are also fabricated to demonstrate the scalability of this approach, achieving η of 11.5%. Our results pave the way toward the implementation of MoS₂ as a material able to boost the shelf life of large-area perovskite solar cells in view of their commercialization.

MoS₂ flakes are proposed as an active buffer layer in hybrid lead halide perovskite solar cells. By preventing the formation of shunt contacts between the perovskite and the metal electrode, MoS₂ flakes act as a protective layer to increase the cell stability, while also easing the hole collection at the anode. Such approach leads to efficient and stable perovskite solar cells.

Simple organic molecules with permanent dipole moments – amino acids and heterocycles – have been successfully employed in bulk-heterojunction organic solar cells as interlayer between photoactive material and electron contact. A large increase of open-circuit voltage and fill factor can be observed for four different polymers as donor material in the photoactive layer. A combination of current–voltage curves, scanning Kelvin-probe atomic force microscopy, ultraviolet photoelectron spectroscopy, and electroluminescence measurements as well as numerical simulations are carried out to clarify in detail the underlying mechanisms. All results fully confirm the hypothesis that the main effect is an accumulation of electrons and a depletion of holes in the photoactive layer in the vicinity of the electron contact induced by a decrease of its effective work function. Further, density functional theory calculations and literature reports of the energy levels of the dipole molecules strongly suggest that the charge carriers tunnel through the thin dipole layer which does however not limit the current. This represents a versatile, simple, and cheap method to realize highly selective contacts which may also be beneficial for other types of solar cells and devices where contact selectivity is crucial.

Simple organic molecules with permanent dipole moments significantly enhance the selectivity of the electron contact in organic solar cells. They modify the work function of Indium Tin Oxide strongly which is investigated by means of scanning Kelvin-probe force microscopy, photoelectron spectroscopy, and electroluminescence in combination with numerical simulations. No preferential tunneling of electrons is needed to consistently explain all results.

On page 4643, Q. Peng and co-workers present a series of star-shaped small molecular cathode interlayer (CIL) materials for photovoltaic applications. They investigate how different pendant polar functionalities with or without mobile counterions influence the photovoltaic properties, including neutral amino groups, quaternary ammonium ions, amino N-oxide, and sulfobetaine ions. A high efficiency of 10.1%, preceding that of the PFN device, was achieved by using the CIL molecule with pendant quaternary ammonium ions.

A three dimensional nature of the charge transport is more effectively described by using the bimodally oriented polymer semiconductor films than unimodally oriented ones as long as good π-stacking is attained in molecular scale. This finding, reported by D. R. Lee, M. S. Kang, D. H. Kim, and co-workers on page 4627, enables another design or engineering consideration for advancing polymer semiconductor systems.

Semitransparent solar cells have attracted significant attention for practical applications, such as windows in buildings and automobiles. Here, semitransparent, highly efficient, 1D nanostructured perovskite solar cells are demonstrated employing anodized aluminum oxide (AAO) as a scaffold layer. The parallel nanopillars in the perovskite layer enable construction of haze-free semitransparent devices without any hysteresis behavior. By controlling the pore size in the AAO, the volume occupied by the perovskite layer can be precisely varied, and the color neutrality of the resulting devices can be achieved. With the incorporation of a transparent cathodic electrode (indium tin oxide) with a buffer layer (MoO_x), a highly efficient semitransparent nanopillared perovskite solar cell is achievable with a power-conversion efficiency of 9.6% (7.5%) and a whole device average visible light transmittance of 33.4% (41.7%). To determine the role of the scaffold layer in improving the photoelectrical properties of the cell, impedance spectroscopy analyses are performed, revealing that the AAO-structured perovskite layer suppresses internal ion diffusion and enables critical improvements in long-term stability under continuous illumination.

For the first time, an anodized aluminum oxide template-based semitransparent perovskite solar cell is demonstrated, which is achieved by forming well-ordered, vertically aligned, nanopillar-structured perovskite layers with a power-conversion efficiency (PCE) of 9.6% at an average visible transmittance (AVT) of 33.4% (or PCE of 7.5% at an AVT of 41.7%).

This study demonstrates high-performance, ternary-blend polymer solar cells by modifying a binary blend bulk heterojunction (PPDT2FBT:PC₇₁BM) with the addition of a ternary component, PPDT2CNBT. PPDT2CNBT is designed to have complementary absorption and deeper frontier energy levels compared to PPDT2FBT, while being based on the same polymeric backbone. A power conversion efficiency of 9.46% is achieved via improvements in both short-circuit current density (J_SC) and open-circuit voltage (V_OC). Interestingly, the V_OC increases with increasing the PPDT2CNBT content in ternary blends. In-depth studies using ultraviolet photoelectron spectroscopy and transient absorption spectroscopy indicate that the two polymers are not electronically homogeneous and function as discrete light harvesting species. The structural similarity between PPDT2CNBT and PPDT2FBT allows the merits of a ternary system to be fully utilized to enhance both J_SC and V_OC without detriment to fill-factor via minimized disruption of semi-crystalline morphology of binary PPDT2FBT:PC₇₁BM blend. Further, by careful analysis, charge carrier transport in this ternary blend is clearly verified to follow parallel-like behavior.

High performance ternary blend polymer solar cells including two donor polymers which share same polymeric backbone are demonstrated, and the charge carrier behavior is investigated as parallel bulk-heterojunction. Real charge carrier behavior of ternary blends is firstly clarified via transient-absorption spectroscopy. Two donors function as discrete light harvester, improving all photovoltaic parameters of the optimized ternary blend polymer solar cells.

A nonfullerene polymer solar cell with a high efficiency of 9.26% is realized by using benzodithiophene–alt–fluorobenzotriazole copolymer J51 as a medium-bandgap polymer donor and the low-bandgap organic semiconductor ITIC with high extinction coefficients as the acceptor.