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Sn-based perovskites have intrinsic defects, such as Sn vacancies, oxidised components (Sn4+), and local lattice strain in the perovskite crystalline structure. In this study, Zn metal powder (Zn0) was introduced to reduce Sn oxidation in the solution step based on the redox potential difference. Additionally, Zn2+ was introduced in the perovskite precursor, which decreased the intrinsic defects and lattice strain of the perovskite films. The diffusion length, particularly that of the hole, increased with a reduction in the lattice strain, and Zn doping led to interfacial energy-level alignment of the perovskite and hole-transporting layers. The reduced lattice strain decreased the defect density and charge carrier recombination of perovskite devices. The power conversion efficiency of the Zn-doped Sn-based perovskite solar cell was improved to 11.39% compared to the 8.56% of the reference device. [ABSTRACT FROM AUTHOR]

Pb‐free Sn‐based perovskite solar cells (PSCs) have significant potential for application in photovoltaic devices because of their suitable bandgap, low exciton binding energy, high carrier mobility, and long diffusion length. However, their performance is hampered by several issues. Sn‐based perovskites are highly susceptible to oxidation, which induces a high concentration of defects and degrades the chemical stability of the perovskite crystals. Herein, the anion formate (HCOO−) can effectively suppress the oxidation of Sn in the pure formamidinium tin triiodide (FASnI3) perovskite without using A‐site cationic additives. Moreover, the presence of formate results in a uniform pinhole‐free perovskite film with a low trap density, reduced charge carrier recombination, and improved charge extraction. Density functional theory calculations show that formate‐treated FASnI3 has improved stability against oxidative Sn degradation. The formate‐treated PSC achieves a power conversion efficiency of 12.11% at a high open‐circuit voltage of 0.71 V. The device exhibits improved stability in ambient air in which it maintained over 80% of its initial power conversion efficiency after 180 min because oxidation is inhibited owing to the strong interaction between Sn and formate. [ABSTRACT FROM AUTHOR]

Quasi‐2D perovskite materials have promise to unlock the full potential of blue perovskite light‐emitting diodes (PeLEDs). However, the efficiency of blue emissive PeLEDs still lags behind the green‐ and red‐emitting counterparts. Here, a multifunctional passivating molecule of (2‐(3,6‐dichloro‐9H‐carbazol‐9‐yl)ethyl)phosphonic acid (36ClCzEPA) that can form a self‐assembled monolayer (SAM) on the indium tin oxide (ITO) electrode is reported. The 36ClCzEPA SAM facilitates hole injection by increasing the work function of ITO through the strong interfacial dipole layer formation at the interface between the perovskite emitter and the ITO electrode. Moreover, it allows a pure‐blue emission and reduces the exciton quenching of luminescence in the perovskite emitter considerably because of its neutral nature, compared to the commonly used acidic PEDOT:PSS. Furthermore, chlorine atoms in the 36ClCzEPA promote well‐ordered crystalline 2D perovskite phases and decrease interfacial trap‐assisted deactivation channels by interfacial passivation. These beneficial characteristics of the 36ClCzEPA SAM yield the excellent luminescence property of PeLEDs with a maximum luminance of 1253 cd m−2 and a peak external quantum efficiency of 4.80% at 473 nm. This work demonstrates that a well‐designed molecule forming an interfacial SAM can be an important component for enhancing the luminescence property of pure‐blue PeLEDs. [ABSTRACT FROM AUTHOR]

Cs-based perovskite nanocrystals (PeNCs) have been considered to be excellent emitters for perovskite light-emitting diodes (PeLEDs) due to their remarkable optoelectronic properties. Still, their poor optical properties are mainly attributed to the deeper defect states induced by the chlorine content, which has hampered the realization of the full potential of blue PeLEDs. Herein, we propose a surface passivation strategy by employing potassium thiocyanate, which is an immobile passivating material (IPM) that considerably improved the structure of the PeNCs by filling halide vacancies and uncoordinated halide sites. Indeed, the photoluminescence quantum yield of the IPM-introduced PeNCs was significantly enhanced to 74.1% compared to that of the reference PeNCs (34.0%). Besides, K+ seized the halide ions in the PeNCs, thereby resulting in excellent colloidal stability. Overall, the PeLEDs achieved an external quantum efficiency of 2.04% and an elongated operating lifetime. Our strategy provides a simple way for breaking down the hurdles limiting the practicability of PeLEDs in display applications. [ABSTRACT FROM AUTHOR]

Among transparent metal oxide semiconductors, systems based on indium oxide currently deliver the best combination of electronic characteristics and optical transmittance, outperforming even the well-established polycrystalline silicon devices. Indium oxide has the unique property that uniform, amorphous films yield superior electronic properties compared to microcrystalline films; for this reason, Ga and Zn hetero-elements are usually added to disrupt crystallization and result in uniformly disordered films. However, dopants have a general tendency to increase the complexity and decrease the mobility of semiconductors and their addition might well be avoided if high-quality, amorphous In2O3 films could be grown without them. In this work, we show that this problem can be resolved by exploiting a synergistic interaction between solution-processed indium oxide (In2O3) and underlying tantalum pentoxide (Ta2O5) dielectric films. We observed that amorphous Ta2O5 inhibits crystallization of In2O3 leading to high-quality amorphous thin films with reduced oxygen deficiencies at the semiconductor/dielectric interface. Transparent Ta2O5/In2O3 TFTs with very low operating voltages were demonstrated with effective field-effect mobilities of up to 23.1 cm2 V−1 s−1 at only 3 V drain–source voltage (VDS) using this approach. Additionally, the suppressed carrier density arising from reduced oxygen deficiencies reduced the drain current at 0 V gate bias (I0) by six orders of magnitude from 0.25 mA to 10.8 nA, compared to a SiO2 reference device. These results highlight the importance of considering an underlying dielectric layer to maximize device performance. [ABSTRACT FROM AUTHOR]

Processing for obtaining compact and uniform perovskite photoactive layers has been intensively studied over the last few years to achieve high power conversion efficiencies (PCEs) in solar cells. Particularly, high quality crystal growth of perovskite layers is critical to enhance device performance. We demonstrate an easy and effective new process for high efficiency p–i–n planar heterojunction structures of perovskite solar cells (PeSCs) by using a compact seed perovskite layer (CSPL). The CSPL assists vertical growth of perovskite crystals and obtains the highly crystalline perovskite photoactive layer, which leads to the reduction in the charge transfer resistance and a longer photoluminescence lifetime. The PeSC device with a CSPL shows a remarkably improved PCE, from 15.07% to 19.25%, with a record open circuit voltage (VOC) of 1.16 V in the p–i–n structure with pure crystal perovskite and negligible current density–voltage hysteresis. Additionally, a PCE of 20.37% was achieved in CSPL assisted n–i–p structure PeSCs. [ABSTRACT FROM AUTHOR]

Abstract: The development of solution‐processed field effect transistors (FETs) based on organic and hybrid materials over the past two decades has demonstrated the incredible potential in these technologies. However, solution processed FETs generally require impracticably high voltages to switch on and off, which precludes their application in low‐power devices and prevent their integration with standard logic circuitry. Here, a universal and environmentally benign solution‐processing method for the preparation of Ta2O5, HfO2 and ZrO2 amorphous dielectric thin films is demonstrated. High mobility CdS FETs are fabricated on such high‐κ dielectric substrates entirely via solution‐processing. The highest mobility, 2.97 cm2 V−1 s−1 is achieved in the device with Ta2O5 dielectric with a low threshold voltage of 1.00 V, which is higher than the mobility of the reference CdS FET with SiO2 dielectric with an order of magnitude decrease in threshold voltage as well. Because these FETs can be operated at less than 5 V, they may potentially be integrated with existing logic and display circuitry without significant signal amplification. This report demonstrates high‐mobility FETs using solution‐processed Ta2O5 dielectrics with drastically reduced power consumption; ≈95% reduction compared to that of the device with a conventional SiO2 gate dielectric. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of inverted perovskite solar cells (PSCs) relies on effectively managing the interface between the hole extraction layer and the light‐absorbing perovskite layer. In this study, we have synthesised (4‐(3,6‐bis(methylthio)‐9H‐carbazol‐9‐yl)butyl)phosphonic acid (MeS‐4PACz), which forms a self‐assembled monolayer (SAM) on the fluorine‐doped tin oxide (FTO) electrode. The molecule‘s methylthio substituents generate a favourable interfacial dipole moment and interact with the perovskite layer. This interaction results in well‐aligned energy levels among the FTO/SAM/perovskite layers, promoting efficient hole extraction and significantly reducing carrier recombination losses. Additionally, the methylthio groups passivate iodide vacancies and interact with Pb2+ ions of the perovskite, reducing defect‐induced trap states and enhancing the crystalline growth of the perovskite layer. Consequently, inverted PSCs incorporating MeS‐4PACz achieve a power conversion efficiency of 25.13 %, along with outstanding photostability. [ABSTRACT FROM AUTHOR]

A tandem system consisting of a combined hematite photoanode/perovskite solar cell is a novel configuration enabling unbiased solar-driven water splitting in a cost-efficient way. However, similar light absorption spectrums between hematite and perovskite, causing significant optical loss of the solar cell located behind the photoelectrochemical cell, have been a critical issue, resulting in a substantial reduction in the overall photoelectrochemical performance in the bias-free tandem system. Herein, we report an efficient thin film hematite/perovskite tandem cell optimized with consideration of both quantum efficiency of the hematite photoanode and optical loss of the solar cell. Ti,Si co-doping with controlled dopability and deposition of transparent NiFeO x co-catalyst on hematite (NiFeO x @Ti:Si–Fe 2 O 3 (t)) allowed for highly improved surface reaction kinetics and charge transport behaviors, endowing our thin film with state-of-the-art performance among thin film hematite photoanodes reported to date, with a photocurrent density of 2.62mAcm−2 at 1.23V RHE and an onset potential of 0.71V. The perovskite solar cell in the thin hematite/solar cell exhibited an anodic shift of V oc from 1.08V to 1.16V and a three-fold increased photocurrent density (15.5mAcm−2) compared to the solar cell of the conventional thick hematite/solar cell system. The assembled dual photoanodes (dual NiFeO x @Ti:Si–Fe 2 O 3) reached a maximum photocurrent density of 4.0mAcm−2 at 1.23V RHE. Our tandem photoelectrochemical system comprising assembled dual thin film NiFeO x @Ti:Si–Fe 2 O 3 /solar cell showed outstanding performance of an unbiased solar-to-hydrogen (STH) conversion efficiency of 4.49%, which is the highest recorded value in the hematite/perovskite tandem cell systems. This work provides a great potential for further development of an unassisted solar water splitting system with the thin film hematite. • The sluggish OER property of thin film hematite was improved by reducing an inevitable Sn content. • Tandem cell efficiency was maximized by reducing optical loss of the solar cell. • The tandem cell (dual NiFeOx@Ti:Si–Fe 2 O 3 /PSC) showed outstanding unbiased STH conversion efficiency of 4.49%. [ABSTRACT FROM AUTHOR]