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Electron transport layer (ETL) materials need to have good photoelectric properties and suitable energy levels to match the perovskite layer. Ti 3 CNT x MXene, a typical two dimensional (2D) solid solution, is a potential ETL material due to excellent conductivity and appropriate work function (WF). Herein, Ti 3 CNT x is obtained by optimizing the X-bit inside MXene, and is firstly used as a new ETL for perovskite solar cells (PSCs). Compared with Ti 3 C 2 T x , Ti 3 CNT x possesses lower WF due to the existence of N-H bonds. And the energy level between Ti 3 CNT x and the perovskite layer is more suited to reduce energy loss. Moreover, Ti 3 CNT x interacts with I- ions to passivate defects, enhancing the quality of the perovskite film. As expected, the better power conversion efficiency (PCE) of Ti 3 CNT x -PSC reaches 20.16 %, which is one of the most outstanding PCE among 2D materials used as ETLs. More interestingly, the Ti 3 CNT x -PSC possesses better stability (the PCE retention rate is 70.3 % after 600 h in the air), as a stronger Pb-O bond can reduce Pb0 formation. This work not only reveals the mechanism of interaction between 2D solid solution materials and perovskite, but also explores the vast application prospect of solid solution MXene in PSCs. [Display omitted] • Ti 3 CNT x is firstly used as a new electron transport layer (ETL) for perovskite solar cells (PSCs). • The energy level between Ti 3 CNT x and the perovskite layer is more suited to reduce energy loss. • Ti 3 CNT x interacts with I- ions to passivate defects, enhancing the quality of the perovskite film. • The PCE of Ti 3 CNT x -PSC reaches 20.16 %, which is one of the most outstanding PCE among 2D materials used as ETLs. • More interestingly, the Ti 3 CNT x -PSC possesses better stability. [ABSTRACT FROM AUTHOR]

Interest in perovskite solar cell (PSC) research is increasing because PSC has a remarkable power conversion efficiency (PCE), which has notably risen to 28.3 %. However, commercialization of PSCs faces a significant obstacle due to their stability issues. This review article primarily focuses on several key aspects of PSCs, including different types of solar cells, their construction and operational mechanisms, efficiency, and overall stability. It explains the structure and functioning of PSCs, covering materials and components used for absorber layer, electron-transport layer, hole-transport layer, and electrodes. This review emphasized stability challenges associated with PSCs and discussed various factors and issues contributing to the degradation of these solar cells over time. It then provided a concise overview of different strategies and ongoing efforts taken to enhance the stability of PSCs. It also summarized various approaches used to improve their durability. In summary, this article offers a comprehensive exploration of PSCs, encompassing their construction, operation, improvement in efficiency, and obstacles related to their long-term stability. Furthermore, it addresses factors influencing PSC stability and outlines future challenges, focusing on prolonging their lifespan and enhancing stability for broader applications. Finally, this article has tackled various possible solutions to address the challenges encountered by the PSCs. [ABSTRACT FROM AUTHOR]

A bilateral self-assembled monolayer (SAM) strategy is proposed to improve the performance of both opaque/translucent and rigid/flexible organic solar cells (OSCs), which have great potential for various high-value applications such as portable, building-integrated and vehicle-integrated photovoltaics. By applying the dipole-controlled SAMs to both ITO/ZnO and ZnO/active layer interfaces, the work function of the ZnO electron transport layer was reduced, which improved charge transport and reduced carrier recombination at the interface. The opaque OSCs with the bilateral SAM demonstrated significant performance improvement with power conversion efficiencies (PCEs) reaching 17.20% and 16.96% for rigid and flexible OSCs. When used in semi-transparent OSCs together with MoO3/Ag/MoO3 electrode, in semi-transparent (ST) OSCs, PCE and average visible transmittance (AVT) can be improved simultaneously, and 10.37% PCE and 36.27% AVT demonstrate a remarkable light utilization efficiency (LUE) of 3.85%. Finally, the large area (10 × 10 cm2) ST-OSC module was fabricated and demonstrated a PCE of 8.17% and LUE of 2.5%, among the best-reported values for inverted module devices. The developed bilateral SAM strategy can be useful in developing high-performance OSCs of both opaque/translucent and rigid/flexible types for various practical applications. [Display omitted] • Bilateral self-assembled monolayer strategy in organic solar cells. • High-performance semi-transparent Large-area organic solar cells. • Optoelectrical properties tuned via interfacial modification. • Balancing average visible transmittance and power conversion efficiency. • Dipole moment boosts charge carrier generation and transfer. [ABSTRACT FROM AUTHOR]

Metal oxide carrier transporting layers have been investigated widely in organic/inorganic lead halide perovskite solar cells (PSCs). Tin oxide (SnO 2) is a promising alternative to the titanium dioxide commonly used in the electron transporting layer (ETL), due to its tunable carrier concentration, high electron mobility, amenability to low-temperature annealing processing, and large energy bandgap. In this study, a facile method was developed for the preparation of a room-temperature-processed SnO 2 electron transporting material that provided a high-quality ETL, leading to PSCs displaying high power conversion efficiency (PCE) and stability. A novel physical ball milling method was first employed to prepare chemically pure ground SnO 2 nanoparticles (G-SnO 2), and a sol–gel process was used to prepare a compact SnO 2 (C-SnO 2) layer. The effects of various types of ETLs (C-SnO 2 , G-SnO 2 , composite G-SnO 2 /C-SnO 2) on the performance of the PSCs are investigated. The composite SnO 2 nanostructure formed a robust ETL having efficient carrier transport properties; accordingly, carrier recombination between the ETL and mixed perovskite was inhibited. PSCs incorporating C-SnO 2 , G-SnO 2 , and G-SnO 2 /C-SnO 2 as ETLs provided PCEs of 16.46, 17.92, and 21.09%, respectively. In addition to their high efficiency, the devices featuring the composite SnO 2 (G-SnO 2 /C-SnO 2) nanostructures possessed excellent long-term stability—they maintained 89% (with encapsulation) and 83% (without encapsulation) of their initial PCEs after 105 days (>2500 h) and 60 days (>1400 h), respectively, when stored under dry ambient air (20 ± 5 RH %). A facile new solid-state synthesis of composite Tin-oxide electron transport layer (ETL) leads to power conversion efficiency up to 21.09% for mixed-cation lead mixed-halide perovskite solar cells. Image 1 • A facile new solid-state synthesis of composite Tin-oxide electron transport layer (ETL) for efficient mixed-cation lead mixed-halide perovskite solar cells. • A novel physical approach—using high-energy ball-milling method introduced to prepare high-quality ground SnO 2 nanoparticle. • The champion power conversion efficiency (PCE) of composite tin oxide nanostructures ETLs reached up to 21.09% and voltage as high as 1.22 V with weaker hysteresis (H = 0.01). • The champion device featuring the composite tin oxide based ETL stable up to 105 days when stored under ambient air (20 ± 5 RH %). [ABSTRACT FROM AUTHOR]

Abstract Developing novel low-cost and efficient electron transport layer (ETL) materials for high-efficiency planar heterojunction perovskite solar cells (PSCs) still remains challenges. Herein, we report a low-temperature colloid-synthesized and solution-deposited strontium stannate SrSnO 3 (SSO) perovskite oxide nanoparticle can be an effective alternative ETL. More importantly, the introduction of yttrium dopant results in a significant improvement in the optoelectronic properties of yttrium-doped SrSnO 3 (YSSO), exhibiting higher electron conductivity and faster electron transfer, as well as better band alignment at ETL/perovskite interface compare to undoped SSO, which is also supported by theory calculation. Consequently, these factors boost all photovoltaic performance parameters, leading to an improvement in the efficiency of planar PSCs. The resulting YSSO-based PSCs exhibit an average efficiency of 17.8% and a maximum power conversion efficiency of 19.0% with the significant reduction of J–V hysteresis, and those devices show high long-term stability as well. Our findings provide the full potential of the perovskite oxide toward future photovoltaic applications, especially for cost-efficient planar PSCs. Graphical abstract fx1 Highlights • First colloid-synthesis and solution-deposition of Y-SrSnO 3 perovskite oxide. • Y-SrSnO 3 is used as an effective ETL for planar perovskite solar cells. • 19.0% power conversion efficiency with negligible hysteresis and high stability. [ABSTRACT FROM AUTHOR]

Abstract In this study, an ideal planar perovskite solar cell (PSC) has been proposed and simulated by using Tungsten Disulfide (WS 2) as an electron transport layer (ETL). Effects of various amphoteric defect states of PSC based on CH 3 NH 3 PbI 3−x X x absorber layer and the interface properties of both ETL and hole transport layer (HTL) are quantitatively analysed by SCAPS-1D numerical simulator. Results show that the device performance is highly influenced by amphoteric defects in the absorber layer rather than the interface defects layer (IDL). It is also revealed that the quantitative tolerable range in CH 3 NH 3 PbI 3−x X x and IDLs are less than 1015 cm−3 and 1016 cm−3, respectively. The PSC exhibits better performance in the range of 10 °C–40 °C and degrades gradually at higher temperature. With the proposed structure, the simulation finds the highest power conversion efficiency (PCE) of PSC to be 25.70% (Voc = 1.056 V, Jsc = 25.483 mA/cm2, and FF = 88.54%). [ABSTRACT FROM AUTHOR]

Abstract Perovskite solar cells (PSCs) are currently exhibiting reproducible high efficiency; the manufacturing of low cost, scalable electron transport layers (ETLs) is becoming increasingly important. However, this remains a challenge for electron transport layers that exhibit excellent optical/electrical properties while being a thin film of simple morphology. Here we demonstrate the PSC of a 2D photonic crystal nanodisk (ND) array ETL that is compact, but greatly enhances light harvesting. The ND array is fabricated by nanosphere lithography using a monolayer of self-assembled polymer spheres as a physical mask. We fabricate ND arrays of various lattice constants simply by controlling the size of the polymer spheres. Optimal ND arrays exhibit strong forward scattering and optical confinement effects, greatly improving light harvesting in the perovskite layer. We also observe that the ND array improves charge transport by reducing contact resistance with the perovskite layer. ND array ETL PSCs reach 19% maximum power conversion efficiency, with low photocurrent-voltage hysteresis and stable photocurrent output. Graphical abstract We demonstrate a perovskite solar cell with a 2D photonic crystal as an electron transport layer and achieve a power conversion efficiency of up to 19% by the effect of improving light harvesting by photonic crystals. fx1 Highlights • We introduce TiO 2 electron-transport layer with a thin-film 2D photonic crystal structure. • We present the surface relief pattern electron-transport layer of a TiO 2 nanodisk array fabricated using nanosphere lithography. • 2D nanodisk perovskite solar cells achieve a maximum power conversion efficiency of 18.7%. • The nanodisk perovskite solar cells also showed low hysteresis in power conversion efficiency and stable efficiency output. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) with an inverted structure have the potential to exhibit both high efficiency and stability, in which the electron transport layer (ETL) plays a crucial role. In this study, we have developed an efficient ETL for inverted structure OSCs by modifying commercially available SnO 2 nanoparticles with a simple molecule 2-(3-(dimethylamino)propyl)− 1,3-dioxo-2,3-dihydro-1 H-benzo[de]isoquinoline-6,7-dicarboxylic acid (NMA). The surface modification effectively eliminates the light soaking issue observed in devices with bare SnO 2. Furthermore, it significantly enhances the efficiency and stability of the photovoltaic devices. With the hybrid ETL, the device based on PM6:L8-BO achieves an outstanding power conversion efficiency (PCE) of 18.33 %. Notably, the champion device exhibits excellent shelf, thermal and photo stabilities. It maintained 99.7 % and 87.1 % of its original efficiency under storage in N 2 and thermal stress at 65 ℃ for 1000 h, respectively. Under continuous 1-sun illumination with maximum power point tracking for 800 h, the device retained 86.6 % of its initial efficiency. Additionally, the hybrid ETL shows good generality on other typical active layer systems based-OSCs. This work presents an effective hybrid ETL approach for the development of high-performance OSCs. [Display omitted] • An efficient hybrid ETL for inverted structure OSCs is reported by modifying SnO 2 nanoparticles with a molecule named NMA. • The surface modification effectively eliminates the light soaking issue observed in devices with bare SnO 2. • The OSC based on the hybrid ETL achieves an outstanding efficiency of 18.33 % and demonstrates excellent stabilities. [ABSTRACT FROM AUTHOR]

We present new architectures in CH 3 NH 3 PbI 3 based planar perovskite solar cells incorporating solution processed SnO 2 /MgO composite electron transport layers that show the highest power outputs ever reported for photovoltaic cells under typical 200–400 lx indoor illumination conditions. When measured under white OSRAM LED lamp (200, 400 lx), the maximum power density values were 20.2 µW/cm 2 (estimated power conversion efficiency, PCE = 25.0%) at 200 lx and 41.6 µW/cm 2 (PCE = 26.9%) at 400 lx which correspond to a ∼ 20% increment compared to solar cells with a SnO 2 layer only (even at standard 1 sun illumination, where the maximum PCE was 19.0%). The thin MgO overlayer leads to more uniform films, reduces interfacial carrier recombination, and leads to better stability. All layers of the cells, except for the two electrodes, are solution processed at low temperatures for low cost processing. Furthermore, ambient indoor conditions represent a milder environment compared to stringent outdoor conditions for a technology that is still looking for a commercial outlet also due to stability concerns. The unparalleled performance here demonstrated, paves the way for perovskite solar cells to contribute strongly to the powering of the indoor electronics of the future (e.g. smart autonomous indoor wireless sensor networks, internet of things etc). [ABSTRACT FROM AUTHOR]

In the present article, the detailed analyses of interface properties and device performance of inorganic perovskite CaMnO 3 -based buffer layer hybrid perovskite solar cell have been undertaken. Analyses are based on ab initio simulations and macroscopic modelling. A thorough study of electronic and optical properties and interface charge dynamics revealed that CaMnO 3 presents a better candidate for the electron transport material in thin film hole transporting material free hybrid perovskite solar cells with the planar architecture than the most common anatase TiO 2 . This result is founded on the more appropriate band gap and better band alignment with the hybrid perovskite, leading to the faster charge carrier mobility, improved charge transfer and reduced exciton recombination. The results from theoretical simulations are justified by the solar cell model, which explored the basic cell characteristics and parameters: open circuit voltage, short circuit current, fill factor and efficiency, as the functions of cell performance factors, like defect density, diffusion length, absorber layer thickness and band offset. Our model suggests an unoptimized device with a photo-conversion efficiency of almost 10% for the low defect concentrations under 10 15 . With efficiency in the upper range for HTM free perovskite solar cells, we propose that the CaMnO 3 -based solar cell poses as an improvement upon the up to now most frequently used ones and provides important step toward their commercialisation. [ABSTRACT FROM AUTHOR]

Electron transport layer (ETL) in perovskite-based solar cells (PSCs) is attractive from the perspective of photon-to-electron conversion efficiency. TiO2thin film is preferred in situations where microstructure, stability and charge transport characteristics are important. In this regard, we illustrate an approach that involves the synthesis of TiO2–pepsin thin film that can be used either as a mesoporous or compact layer depending on the device architecture of PSC devices. It was observed that pepsin acts as organic glue to TiO2nanoparticles and facilitates in controlling morphology of the thin film. The addition of pepsin did not have any adverse effect on TiO2anatase phase. Thickness and roughness of mesoporous and compact TiO2thin film suggested that controlled agglomeration can be achieved by tuning the concentration of pepsin in the precursor colloidal solution. The spin-coated thin films indicated high bulk mobility (205 cm2V−1 s−1) and good thermal stability over a wide range temperature (25–700°C). Furthermore, in the presence of pepsin group in TiO2thin film, the inherent optical properties were retained, as confirmed by UV–vis analysis. [ABSTRACT FROM PUBLISHER]

As a new generation of photovoltaics, perovskite solar cells (PSCs) have been intensively studies in recent years due to their high-efficiency, low-cost and ease of fabrication. For a typical high-performance PSC, electron transport layer (ETL) plays an important role in selectively extracting and transporting photo-generated electrons from perovskite to the electrode. In this paper, for the first time, we found that a well-organized In 2 S 3 nanoflakes array can be used in PSCs with a high power conversion efficiency (PCE) of 18.22% with less hysteresis. In comparison, PSCs based on TiO 2 ETL showed a much lower PCE of 15.70%. Experimental results clearly illustrate that the optimized band structure, enhanced light tapping and low recombination of photo-generated carriers in In 2 S 3 ETL based devices leads to this enhanced performance. Noteworthily, such In 2 S 3 ETLs are simple and solution processable at low-temperature (≤80 °C), which might provide new avenue for low-cost and solution-processed photovoltaics. [ABSTRACT FROM AUTHOR]

Two wide bandgap copolymers based on bulky indacenodithiophene (IDT) and alkoxylated benzothiadiazole units (PIDTBTO-T and PIDTBTO-TT) with the thiophene or thieno[3,2-b]thiophene (TT) π-bridge are designed and synthesized. The effect of π-bridge on the π-π packing, optical, carrier transport, nano-sized phase separation and photovoltaic properties of the copolymers are investigated in depth. In comparison with the PIDTBTO-T-based counterpart, the best performance solar cell based on PIDTBTO-TT exhibits a higher power conversion efficiency (PCE) of 8.15% which is mainly attributed to the formation of a fibrous network for the active layer based on PIDTBTO-TT. Furthermore, when a novel hybrid electron transport layer (PDIN:PFN) is introduced into a tandem solar cell using the PIDTBTO-TT-based device and a PTB7-Th-based device as the bottom and top cell components, respectively, the resulting solar cell exhibits an outstanding PCE of 11.15% with a large open circuit voltage of 1.70 V. To the best of our knowledge, the PCEs of 8.15% and 11.15% are the highest values reported to date for the single-junction and tandem solar cells using IDT-based copolymers, respectively. Our results demonstrate that the π-bridge modulation is effective in adjusting the charge carrier mobility and photovoltaic performance of IDT-based wide bandgap copolymers for single-junction and tandem devices. [ABSTRACT FROM AUTHOR]

Electron transport layer (ETL) is a key component in the perovskite solar cells (PSCs). Low temperature, even room temperature deposition technique for ETLs is especially intriguing for flexible solar cell fabrication on polymer substrates. Here, we proposed a facile amine gas fuming strategy to prepare SnO 2 ETLs at room temperature without thermal annealing. It is found that the SnO 2 films treated with methylamine or other amine gases are smoother and more compact than the SnO 2 films with thermal annealing. A base-catalyzed densification mechanism is proposed that the SnO 2 colloidal is converted into compact film through particle connections and attachments facilitated by basic amine gas treatments. XRD, FTIR and TEM were used to verify the densification mechanism. With methylamine treated SnO 2 ETLs, the rigid and flexible PSCs achieved high PCEs of 20.36% and 19.80%, respectively. The flexible PSCs with the annealing free SnO 2 ETLs showed excellent flexibility with 94.5% of the initial PCE remaining after 3000 bending cycles. The amine fuming method provides a new and facile way for annealing free deposition of charge transport layers for flexible solar cells and optoelectronics. [Display omitted] SnO 2 electron transport layer (ETL) is deposited through amine gas fuming treatment without thermal annealing. The flexible PSCs based on the annealing-free SnO 2 ETL demonstrated superior performance and mechanical robustness. • Amine gas fuming treatment produces compact SnO 2 ETL for PSCs without thermal annealing. • The PSCs with annealing-free ETLs show higher PCE (20.36%) compared to the PSCs with annealed SnO 2 ETLs (17.42%). • The flexible PSCs with amine gas fuming ETL achieve PCE of 19.80% and maintain 94.5% PCE after 3000 bending cycles. [ABSTRACT FROM AUTHOR]

Due to the continuous increase in power conversion efficiencies (PCEs), perovskite solar cells (PSCs) are widely considered as the most promising technology for third generation photovoltaics. Improving optical absorption while reducing electrical losses is still a challenge towards attaining PCE values closer to the Shockley-Queisser limit. However, frequently used strategies to improve light absorption (e.g. via texturing the front surface) often cause electrical recombination losses. Here, we successfully relaxed the competing mechanisms between electrical and optical properties by integrating a modulated textured substrate and an amorphous metal nitride interface modification layer to combine enhanced light scattering and reducing interfacial recombination losses in PSCs. This comprehensive electro-optical management presents several advantages, including increased light absorption, promoting bandgap alignment and passivating the underlying perovskite defects. Consequently, the resulting MAPbI 3 solar cells exhibit a high open-circuit voltage of 1.17 V and the concomitant high PCE of 21.84%. In addition, we also use numerical simulations to propose approaches towards achieving high efficiency (PCE >30%) PSCs. Besides expanding the pool of available strategies for improving the efficiency of PSCs, from photon management to interface engineering, our work also offers a systematic guidance for the design and fabrication of high performance photovoltaic devices. [Display omitted] Upgraded PSCs (MST-PSCs) with excellent PCE have been designed and achieved by integrating a surface textured substrate and advance amorphous-metal-nitride interlayer. Approaches to attain > 30% efficiency of PSCs has been explored. Comprehensive insights into the interaction between the light management, interface polarities, and the performance of the device have also been elucidated in detail. • Upgraded PSCs with advanced IML and light scattering have been proposed. • Comprehensive electro-optical management boosts device performance. • Approaches towards achieving > 30% efficiency have been proposed. • Providing an advanced metal nitride ETL as an alternative for future PSCs. [ABSTRACT FROM AUTHOR]

Low operational stability of perovskite solar cells represents a major obstacle for practical implementation of this technology. In that context, ZnO was considered as a promising electron transport material with suppressed oxidizing properties as compared to SnO 2 and TiO 2. However, the first studies revealed the chemical instability of the interface between lead halide perovskites and zinc oxide, whereas the underlying reasons are still under active debates. Still, the interfacial instability issues made ZnO a largely overlooked electron transport layer despite its excellent optoelectronic properties. This study presents a novel approach to the zinc oxide surface modification with methylammonium iodide that suppresses further reactions with the adjacent perovskite absorber layer. Consequently, the solar cells based on CH 3 NH 3 PbI 3 exhibited largely improved thermal stability. Furthermore, the application of Cs 0.12 [HC(NH 2) 2 ] 0.88 PbI 3 as absorber material in devices with the modified ZnO electron transport layer resulted in 82% retention of the initial efficiency after aging for 2100 h at 50 mW cm−2 and 65 °C. On the contrary, the reference cells fabricated with the pristine non-modified ZnO degraded completely under the same conditions. We attribute the revealed stabilization effect of the methylammonium iodide treatment to passivation of the reactive ZnO surface and inhibiting the parasitic interfacial chemistry leading to the lead iodide formation. To our best knowledge, here we have demonstrated the highest operational stability for the perovskite cells when using ZnO-based ETL. Reactive modification of zinc oxide with methylammonium iodide boosts the operational stability of perovskite solar cells. The competitive power conversion efficiency of 18.9% and 2000 h operation stability under continuous illumination was achieved for perovskite solar cells with MAI modified ZnO electron transport layer. The stability increase was attributed to inhibition of surface lead iodide formation [Display omitted] [ABSTRACT FROM AUTHOR]

Constructing electron transport layer (ETL) with higher carrier mobility and suitable bandgap is of key importance as it greatly influences the photovoltaic performance of perovskite solar cells (PSCs). Zn 2 SnO 4 (ZTO) carries a high electron mobility of 10–30 cm2 V−1 s−1, an order of magnitude over the widely used TiO 2 ETL in PSCs, rendering it an excellent alternative to TiO 2 ETL. Herein, we report a simple yet robust polymer-templating route to interconnected, hierarchically structured, porous ZTO nanospheres as an efficient ETL for high-performance organolead halide PSCs. The porous ZTO nanospheres ETL, composed of an assembly of 4.5-nm ZTO nanoparticles on the surface of porous nanosphere possessing 80–100 nm cavity, renders markedly improved light absorption, enhanced electron extraction, facilitated charger transportation, and suppressed carrier recombination in the resulting PSCs, which exhibit a power conversion efficiency (PCE) of 17.14%, greatly outperforming the device based on the ZTO nanoparticles (14.02%; i.e., without porosity). As such, the strategy for crafting porous yet hierarchically structured semiconductors with high carrier mobility may open up an avenue to create robust ETL, and by extension, hole transport layer (HTL) for high-performance optoelectronics. The porous Zn 2 SnO 4 nanospheres electron transport layer (ETL) prepared by polymer-templating route with large porosity, high surface area, and three-dimensional interconnected structure renders markedly improved light absorption, enhanced electron extraction, facilitated charger transportation, and suppressed carrier recombination in the resulting PSCs. Image 1 • A polymer-templating route to interconnected, hierarchically structured ETL for PSCs with markedly improved efficiency is developed. • Hierarchically structured ZTO nanospheres as ETL for PSCs renders enhanced light absorption, electron extraction and transportation. • The strategy of crafting hierarchically structured semiconductors opens up an avenue to create robust ETL for optoelectronics. [ABSTRACT FROM AUTHOR]

The design and development of novel materials with superior charge transport capabilities plays an essential role for advancing the performance of electronic devices. Ternary and doped oxides can be potentially explored because of their tailored electronic energy levels, exceptional physical properties, high electrical conductivity, excellent robustness and enhanced chemical stability. Here, a route for improving metal oxide characteristics is proposed by preparing a novel ternary oxide, namely, carbon-doped tantalum dioxyfluoride (TaO 2 FC x) through a straightforward synthetic route and exploring its effectiveness as an electron transport material in optoelectronic devices based on organic semiconductors. Among other devices, we fabricated fluorescent green organic light emitting diodes with current efficiencies of 16.53 cd/A and single-junction non-fullerene organic solar cells reaching power conversion efficiencies of 14.14% when using the novel oxide as electron transport material. Our devices also exhibited the additional advantage of high operational and temporal stability. Non-fullerene OSCs based on the novel compound showed unprecedented stability when exposed to UV light in air due to the non-defective nature of TaO 2 FC x. We employed a tank of experiments combined with theoretical calculations to unravel the performance merits of this novel compound. This study reveals that properly engineered ternary oxides, in particular, TaO 2 FC x or analogous materials can enable efficient electron transport in organic optoelectronics and are proposed as an attractive route for the broader field of optoelectronic devices including metal-organic perovskite, colloidal quantum dot and silicon optoelectronics. A superior electron transport material namely carbon-doped tantalum dioxyfluoride for optoelectronic applications was developed. The novel compound exhibited ideal energetic alignment with organic semiconductors, low refractive index and high conductivity hence achieving current efficiencies reaching 16.53 cd/A in OLEDs and power conversion efficiencies of up to 14.14% in non-fullerene OSCs with the additional advantage of high operational and temporal stability. Image 1 • Design and development of a carbon-doped tantalum dioxyfluoride as electron transport material. • The novel oxide exhibits high electron conductivity, high transparency, low refractive index and high hydrophobicity. • Fluorescent green OLEDs with current efficiencies of 16.53 cd/A. • Single-junction non-fullerene OSCs reaching PCEs of 14.14 %. [ABSTRACT FROM AUTHOR]

Oxide/perovskite heterojunction contact is important for realizing high performance and stable perovskite solar cells (PSCs). However, the development of ZnO/perovskite heterojunction contact is plagued by the poor chemical compatibility at ZnO/organic-inorganic perovskite interface. Nevertheless, the ZnO/inorganic perovskite heterojunction contact exhibits potential applications in all-inorganic PSCs. In this study, all-inorganic CsPbI 2 Br PSCs based on ZnO/perovskite heterojunction contact have been successfully realized at low temperature process below 150 °C and delivered an excellent power efficiency conversion of 14.78% with a high open-circuit voltage (V oc) of 1.21 V and a truly extraordinary fill factor (FF) of 81.42%. Compared to SnO 2 -based PSCs, the better band alignment between ZnO ETL and perovskite contributed larger built-in potential, resulting in superior electron extraction capability and effective interfacial recombination suppression. The better perovskite film quality and improved interface contact of ETL/perovskite contributed to better air and thermal stability of ZnO-based perovskite devices. These researches have proved the unlimited possibilities for ZnO as ETL in all-inorganic perovskite solar cells. All-inorganic CsPbI 2 Br PSCs based on ZnO/perovskite heterojunction contact processed below 150 °C were achieved with a PCE of 14.78%, a V oc of 1.21 V and an FF of 81.42%. Compared to SnO 2 -based PSCs, the better band alignment of ZnO/perovskite contact contributed larger built-in potential, resulting in superior electron extraction capability and effective interfacial recombination suppression. The better perovskite film quality and improved interface contact contributed to good air and thermal stability. Image 1 • High performance PSCs with efficiency of 14.8% and fill factor of 81.4% are achieved based on ZnO/CsPbI 2 Br contact. • The better band alignment between ZnO and perovskite contributed larger built-in potential. • ZnO/CsPbI 2 Br contact results in superior electron extraction capability and effective interfacial recombination suppression. • The unencapsulated device exhibited better air and thermal stability due to improved interface contact of ZnO/perovskite. [ABSTRACT FROM AUTHOR]

The optimal interface of perovskite solar cells contributes to efficient charge collection and transport for leading high power conversion efficiency. Despite SnO 2 is a commonly used electron transport materials for perovskite solar cells due to wide band gap and n -type semiconducting property, shallow conduction band edge and low electrical conductivity of pristine SnO 2 limit the full potential for efficient electron extraction from perovskite absorber. To improve the electrical property of SnO 2 , we design and synthesize Zr-doped SnO 2 nanoparticles, in which tailored electronic structure affords enhanced conductivity, adjusted energy levels and excellence in electron extraction capability. Consequently, the champion device employing Zr-doped SnO 2 nanoparticles achieves a power conversion efficiency of 19.54%, while the pristine SnO 2 nanoparticles yield 17.30% under 100 mW cm−2 illumination. The systematic device analyses confirm that Zr-doped SnO 2 delivers reduced interfacial resistance, reduced current leakage and suppressed charge recombination, which leads to not only the enhanced power conversion efficiency but also reduced hysteresis for the planar perovskite solar cells. Image 1 • Zr-doped SnO 2 nanoparticles have been studied systematically to be used in perovskite solar cells. • Zr-doping improved the optoelectronic properties of SnO 2 for the electron transport layer. • Zr-doped SnO 2 nanoparticles improved the efficiency of the solar cells from 17.30% to 19.54%. [ABSTRACT FROM AUTHOR]