Search

Zinc oxide (ZnO) is a promising electron‐transport layer (ETL) in thin‐film photovoltaics. However, the poor chemical compatibility between commonly used sol–gel‐derived ZnO nanostructures and organo–metal halide perovskites makes it highly challenging to obtain efficient and stable perovskite solar cells (PSCs). Here, a novel approach is reported for low‐temperature processed pure ZnO ETLs for planar heterojunction PSCs based on ZnO quantum dots (QDs) stabilized by dimethyl sulfoxide (DMSO) as easily removable solvent molecules. With no need for the ETL doping or surface modification, the champion PSC comprising the mixed‐cation and mixed‐halide Cs5(MA0.17FA0.83)95Pb(I0.83Br0.17)3 absorber layer reaches a maximum power conversion efficiency of 20.05%, which is significantly higher than that obtained for a reference device based on a standard sol–gel‐derived ZnO nanostructured layer (17.78%). Thus, along with the observed better operational stability in ambient conditions and elevated temperature, the champion device achieves the state‐of‐the‐art performance among reported non‐passivated pure ZnO ETL‐based PSCs. The improved photovoltaic performance is attributed to both a higher uniformity of the surface morphology and a lower defects density of films based on the organometallic‐derived QDs that are likely to ensure the enhanced stability of the ZnO/perovskite interface. [ABSTRACT FROM AUTHOR]

Summary: Titanium dioxide (TiO2) is the most often utilised electron transport layer (ETL) in perovskite solar cells (PSCs). Owing to its inherent limitations such as low electron mobility, inadmissible charge accumulation and recombination, many efforts have been devoted to the surface alteration of TiO2 to enhance the performance of PSCs. However, the key mechanism of this improvement is still unclear. Here, we study the mesoporous TiO2 (ms‐TiO2) ETL passivated by Nb2O5 and Ta2O5. The ETL modified PSCs show increased open‐circuit voltage (VOC). Power conversion efficiency (PCE) of 18.70%, 20.71%, and 20.96% were obtained for the devices with ms‐TiO2, ms‐TiO2/Nb2O5 and ms‐TiO2/Ta2O5 ETL. Furthermore, the hysteresis index (HI) of pristine ms‐TiO2 (HI = 4.91%) based devices are much higher than the Nb2O5 (HI = 2.75%) and Ta2O5 (HI = 1.19%) based devices. Our characterization results reveal that the carrier recombination is the main factor in increasing the VOC rather than energy band alignment once we passivate the surface of the ETL. This work is helpful in providing new insights into the surface modification of the mesoscopic ETL. [ABSTRACT FROM AUTHOR]

There has been tremendous advancement in the field of perovskite photovoltaics by means of interfacial engineering, compositional engineering and optimization of charge collection efficiency. The large bandgap oxides deposited using atomic layer deposition (ALD) technique have proven to be successfully passivating the interfacial defects owing to the advantages offered by this technique. Here, the effect of surface modification of mesoporous TiO2 (ms‐TiO2) layer with a transition metal oxide named niobium pentoxide (Nb2O5) deposited by ALD technique on the performance and stability of perovskite solar cells (PSCs) is investigated. The results reveal that functionalization with ultrathin Nb2O5 layer improve the optoelectronic properties and morphology of the deposited perovskite films. Moreover, the charge transfer is improved and hence the interfacial recombination is reduced. This results in improved power conversion efficiency (PCE) from 19.11% to 21.04% and open‐circuit voltage (VOC) from 1.118 to 1.147 V for the modified champion device. Additionally, the device shows negligible hysteresis with enhanced shelf life thermal and UV stabilities. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) fabricated with a normal mesoscopic negative‐intrinsic‐positive (n‐i‐p) device structure have shown a great promise for further developments ever since their enhanced performance with high power conversion efficiency (PCE, 25.2%) and excellent reproducibility. The electron transporting layer (ETL) employed in such PSCs has been a critical component for improving their performance. The present work focuses on the synthesis of high‐quality Ru‐doped compact TiO2 (c‐TiO2) ETLs (Ru:c‐TiO2) by a simple spin‐coating technique. Further, the role of Ru4+ cation doping in c‐TiO2 is discussed in detail. A systematic study revealed that the Ru‐doping not only significantly influences the open‐circuit voltage (Voc), current density (Jsc), and fill factor (FF) but also suppresses the charge recombination in the perovskite devices. The PSCs prepared using Ru‐c‐TiO2 ETLs with optimum Ru‐doping content exhibited PCEs of 19.48% for planar and 20.87% for mesoscopic device architecture with enhanced photovoltage. Additionally, the fabricated PSC devices based on 1.5% Ru:c‐TiO2 ETLs exhibited air stability over 200 days, which is much higher than that of a control device. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C60 derivative (C60‐BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO2 ETL with C60‐BCT@Au NPs substantially improves the charge extraction efficiency from the perovskite layer and suppresses charge recombination processes. Consequently, the resulting device yields a champion efficiency of 19.08% as well as devaluation in hysteresis. In addition, the unencapsulated PSCs with c‐TiO2/C60‐BCT@Au NPs ETL retain 83% and 90% of their original PCEs after 500 h storage in air and exposure to continuous UV illumination for 200 h, respectively. This study provides an effective method to address the electron transporting issues between perovskite and c‐TiO2 ETL for developing stable and efficient PSCs. [ABSTRACT FROM AUTHOR]

Due to its excellent thermal stability and high performance, inorganic cesium lead mixed halide (ABX3, where A = Cs, B = Pb, and X = I/Br) all‐inorganic perovskite solar cells (IPVSCs) have attracted much interest in optoelectronic applications. However, the film quality, enough absorption by desired film thickness, and nature of partial replacement of cations determine the stability of the CsPbI2Br perovskite films. Herein, a hot air method is used to control the thickness and morphology of the CsPbI2Br perovskite thin film, and the A‐site (herein, Cs+) cation is partially incorporated by rubidium (Rb+) cations for making the stable black phase under ambient conditions. The Rb cation‐incorporated Cs1−xRbxPbI2Br (x = 0–0.03) perovskite thin films exhibit high crystallinity, uniform grains, extremely dense, and pinhole‐free morphology. The fabricated device with its Cs0.99Rb0.01PbI2Br perovskite composition with poly(3‐hexylthiophene‐2,5‐diyl) as a hole‐transporting layer exhibits a power conversion efficiency (PCE) of 17.16%, which is much higher than that of CsPbI2Br‐based IPVSCs. The fabricated Cs0.99Rb0.01PbI2Br‐based IPVSC devices retain >90% of the initial efficiency over 120 h at 65 °C thermal stress, which is much higher than that of CsPbI2Br samples. [ABSTRACT FROM AUTHOR]

Quantum dot solar cells (QDSCs) are attractive technology for commercialization, owing to various advantages, such as cost effectiveness, and require relatively simple device fabrication processes. The properties of semiconductor quantum dots (QDs), such as band gap energy, optical absorption, and carrier transport, can be effectively tuned by modulating their size and shape. Two types of architectures of QDSCs have been developed: 1) photoelectric cells (PECs) fabricated from QDs sensitized on nanostructured TiO2, and 2) photovoltaic cells fabricated from a Schottky junction and heterojunction. Different types of semiconductor QDs, such as a secondary, ternary, quaternary, and perovskite semiconductors, are used for the advancement of QDSCs. The major challenge in QDSCs is the presence of defects in QDs, which lead to recombination reactions and thereby limit the overall performance of the device. To tackle this problem, several strategies, such as the implementation of a passivation layer over the QD layer and the preparation of core–shell structures, have been developed. This review covers aspects of QDSCs that are essential to understand for further improvement in this field and their commercialization. [ABSTRACT FROM AUTHOR]

(DOI: 10.1002/solr.202300174) The above article, first published online as an accepted article on 25 April 2023 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the authors, the Editor‐in‐Chief Anna Troeger, and Wiley‐VCH Verlag GmbH. The authors requested a withdrawal due to problems with the reproducibility of the reported experimental data. [ABSTRACT FROM AUTHOR]

A secondary hydrothermal process was used to synthesize exotic hollow nanostructures of rutile TiO2 as an electron-transport layer for perovskite solar cells. The prepared nanostructures were used in combination with methylammonium lead iodide (MAPbI3) perovskite, and their photovoltaic properties were studied. This core-shell architecture of a perovskite enveloped by TiO2 provides an enhanced surface area, better contact with the perovskite because of the larger adsorption area, and effective light penetration. Our results revealed that the hollow nanoflowers exhibit a photocurrent density of 21.05 mA cm−2, an open-circuit voltage of 0.916 V, and a fill factor of 0.66, which leads to a power conversion efficiency of 12.72 %. These results were also verified by electrochemical impedance spectroscopy and time-resolved photoluminescence spectroscopy. Furthermore, the effect of the wetting time was studied, and our results revealed that a minimum time of 100 s is required for good penetration of a MAPbI3/γ-butyrolactone solution. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) absorber thin films are prepared by sulfurization of sputtered Cu/Sn/Zn (CZT) stacked metallic precursor. The modified sulfurization process is adapted to prepare photovoltaic quality CZTS films. Specifically, sputtered CZT precursor films are sulfurized in sulfur powder contained graphite box using rapid thermal processing furnace at 580 °C for 10 min, in N2(95%) + H2S (5%) atmosphere. The Cu-poor CZTS films with various Cu/(Zn+Sn) ratio are prepared by varying Cu layer deposition time. The effect of Cu/(Zn+Sn) ratio on the properties of CZTS films is investigated. The CZTS thin film solar cells with Cu/(Zn+Sn)=0.76 shows best conversion efficiency of 5.1% (Voc: 573 mV, Jsc: 18.38 mA/cm2, FF: 0.48%, and active area: 0.31 cm2). (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Comparative studies on the properties of Cu 2 ZnSnS 4 (CZTS) thin films and performance of CZTS thin film solar cells (TFSCs) prepared by different sulfurization types such as commerical furnace (CF) and rapid thermal annealing (RTA) systems have been investigated. The CZTS thin film prepared using CF showed the dense microstructure with many voids and secondary phases, while that prepared using RTA showed the dense microstructure without void and with some secondary phases. The RTA annealed CZTS TFSC have shown better performance than that prepared using CF. The best performance of CZTS TFSC using RTA was 1.9% efficiency ( V oc : 505 mV, J sc : 7.5 mA/cm 2 and FF: 50.2%). [ABSTRACT FROM AUTHOR]

In present report, we have successfully synthesized nanocrystalline nanosheet-like CdS thin films on ultrasonically cleaned bare and FTO-coated glass substrates by using self-organized arrested precipitation technique. The effect of annealing on opto-structural, morphological and electrical properties were studied by using UV-Vis-NIR spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS) analyzer, X-ray photoelectron spectroscopy (XPS), electrical conductivity and thermoelectric power measurement. The UV-Vis-NIR studies revealed that band gap energy is varied from 2.23-2.05 and 2.00 eV with increase in deposition time and post annealing temperature (373 K), respectively. Also, optical absorption data indicates transition mechanism type is direct and allowed. The XRD study revealed that films are nanocrystalline in nature and pure cubic crystal structure with crystallite size ranging from 61 to 86 nm. FESEM micrographs confirm material is well adherent, pin-hole free over entire substrate surface. XPS shows presence of Cd and S ions and EDS confirms Stoichiometric film formation. Finally as deposited and annealed (372 K for 1 h) thin films were tested for their photoelectrochemical properties. PEC results revealed that the annealed CdS thin film shows 0.846 mA cm short current density ( J) with 0.10 % highest conversion efficiency ( η). [ABSTRACT FROM AUTHOR]

CuZnSnS (CZTS) absorber layers were prepared from copper acetate, zinc acetate, tin chloride, and thiourea in a solution of methanol, ethylenediamine, and ethanolamine using a sol-gel spin-coating method. Sol-gel precursor solutions were prepared with different metal salt ratios, and the effects on film growth, optical properties, and crystal properties of CZTS films were investigated. In addition, the role of sulfurization temperature on grain size of CZTS and formation of the MoS layer at the CZTS and Mo interface were investigated. By changing the metal salt ratio in the precursor solution, a Zn-rich and Cu-poor condition in the CZTS film was obtained. By preparing Zn-rich and Cu-poor CZTS film with a thinner MoS layer at a lower sulfurization temperature, the CZTS cell efficiency was improved, and a conversion efficiency of 1.22 % was obtained. [ABSTRACT FROM AUTHOR]

Cadmium sulfide (CdS) has been employed as an alternative acceptor for planar heterojunction solar cell based on copper phthalocyanine (CuPc). Spin-coated poly-3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) on indium tin oxide (ITO)-coated glass substrates was used for the vacuum deposition of CuPc and CdS planar heterojunction. In the present study, we have fabricated two different architectures of CuPc/CdS devices: (1) ITO/PEDOT:PSS/CuPc/CdS/Al and (2) ITO/PEDOT:PSS/CuPc/CdS/LiF/Al. Our results indicate that the CdS could effectively facilitate charge transport in the nanostructured network, and be a good acceptor. The fabricated bare CuPc/CdS device shows 0.13 % conversion efficiency while incorporation of LiF layer between CuPc/CdS and Al contact facilitates low-recombination rate results ~43 % enhancement in efficiency. The ITO/PEDOT:PSS/CuPc/CdS/LiF/Al device shows 0.30 % power conversion efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Chemically functionalized plant oils, viz. acrylated epoxidized soybean oil (AESO) and maleinized acrylated epoxidized soybean oil (MAESO), were used as bio-based binders for the TiO2 electrodes of dye-sensitized solar cells (DSSC). The surface roughness and number of appropriate pores were increased in the TiO2 films prepared using the plant oil binders in comparison with the film prepared using polyethylene glycol (PEG), due to the larger number of functionalities. The short circuit photocurrent (I SC) and open circuit photovoltage (V OC) were increased, and the conversion efficiency was significantly improved, in the cell using the plant oil binders. [Copyright &y& Elsevier]

• All-inorganic perovskite solar cells have attracted great interest due to its high thermal stability. • Dynamic hot-air (DHA) assisted method has been used for the deposition of CsPbI 2 Br perovskite thin films. • Alkaline earth metal barium (Ba 2+ ) doped CsPbI 2 Br perovskite thin films were sythesized in order to improve its phase stability. • The BaI 2 :CsPbI 2 Br based perovskite devices show average 14.85% power conversion efficiency and maintain >92% initial efficiency over 300 h. • The large area devices exhibited 13.78% efficiency revealed feasibility of this DHA method towards upscalling. • This DHA method facilitates a wide processing window for upscaling the thermally stable inorganic perovskite solar cells. On 3rd August 2019 National Renewable Energy Laboratory (NREL) announced a new world record of 25.2% power conversion efficiency (PCE) for the hottest photovoltaic material known as perovskites. The growth in popularity and substantial improvement in the efficiency of perovskites since their discovery in 2009 is demonstrated by over 6000 publications in 2018. Although, the current world record efficiency has been reported for organic-inorganic halide perovskite, all devices were fabricated in controlled inert conditions and organic cations suffer from poor stability. Therefore, replacement of conventional organic cations by inorganic cations is one of the most promising approaches to make thermally stable photovoltaics. However, all-inorganic perovskite solar cells (PSCs) (herein AIPSCs) composition and deposition techniques limit the real-time stability. This article previews the dynamic hot air (DHA) method used for making CsPbI 2 Br-based perovskites with improved air-thermal stability using barium (Ba2+) alkaline earth metal ion doping. Interestingly, the feasibility of this DHA method toward large area fabrication is also demonstrated. [ABSTRACT FROM AUTHOR]

Perovskite Solar Cells: Simultaneous Improved Performance and Thermal Stability of Planar Metal Ion Incorporated CsPbI2Br All-Inorganic Perovskite Solar Cells Based on MgZnO Nanocrystalline Electron Transporting Layer (Adv. Keywords: degradation; MgZnO electron transporting layer; Mn2+ incorporated CsPbI2Br Degradation, MgZnO electron transporting layer, Mn2+ incorporated CsPbI2Br. [Extracted from the article]

The quality of perovskite films plays a crucial role in improving the optoelectronic properties and performance of perovskite solar cells (PSCs). Herein, high‐quality CsxFA1−xPbI3 perovskite films with different compositions (x = 0, 5, 10, and 15) are achieved by controlling the amount of cesium chloride (CsCl) in the respective FAPbI3 precursor solution. The effects of CsCl addition on the morphological and optoelectronic properties of the resulting perovskite films and on the performance of the corresponding devices are systematically studied. Introduction of CsCl into FAPbI3 shows a great potential to stabilize the α‐FAPbI3 perovskite phase by forming CsxFA1−xPbI3 films with improved morphology and carrier lifetimes. With an optimal 10 mol% CsCl additive, the average power conversion efficiency (PCE) is increased from 16.83 ± 0.30% for the reference FAPbI3‐based PSCs to 18.87 ± 0.25% (with a steady‐state PCE of 18.89%). Moreover, the optimized device performance is more stable after 20 days than the controlled one under ≈40% humidity in air. [ABSTRACT FROM AUTHOR]

Mixed‐cation perovskite solar cells (PSCs) have become of enormous interest because of their excellent efficiency, which is now crossing 23.7%. Their broader absorption, relatively high stability with low fabrication cost compared to conventional single phase ABX3 perovskites (where A: organic cation; B: divalent metal ion; and X: halide anion) are key properties of mixed‐halide mixed‐cation perovskites. However, the controlling reaction rate and formation of extremely dense, textured, smooth, and large grains of perovskite layer is a crucial task in order to achieve highly efficient PSCs. Herein, a new simple dual‐retarded reaction processing (DRP) method is developed to synthesize a high‐quality mixed‐cation (FAPbI3)0.85(MAPbBr3)0.15 (where MAPbBr3 stands for methylammonium lead bromide and FAPbI3 stands for formamidinium lead iodide) perovskite thin film via intermediate phase and incorporation of nitrogen‐doped reduced graphene oxide (N‐rGO). The reaction rate is retarded via two steps: first the formation of intermediate phase and second the interaction of the nitrogen groups on N‐rGO with hydrogen atoms from formamidinium cations. This DRP process allows for the fabrication of PSCs with maximum conversion efficiency higher than 20.3%. Controlling the retarding reaction process enhances perovskite crystal growth, resulting in >20% efficiency. The dual retarding process enables large perovskite thin film grain size, which facilitates enhanced photovoltaic performance. [ABSTRACT FROM AUTHOR]

Engineered hollow TiO2 nanostructure‐based perovskite solar cells: The cover image illustrates hydrothermally processed 1D and 3D hollow rutile TiO2 nanostructures as an efficient electron‐transporting layer (ETL) for perovskite solar cells (PSCs). In the past few years PSCs showed renewed high interest as promising light‐harvesting materials for future photovoltaic technology. The type of conductivity (n or p), electron/hole mobility, and surface area of the ETL and hole‐transporting layer (HTL) play key roles in the ultimate PSC properties. Implementation of a defect‐free 1D nanostructured n‐type ETL is one of the most promising approaches towards boosting efficiency of PSCs. Here, we have synthesized solid TiO2 nanostructures from titanium tetra‐isopropoxide (TTIP) precursor in equal volume concentrations of H2O and HCl at 180 °C. These solid nanostructures were etched using HCl/H2O (2:1 v/v) at 150 °C to form hollow 1D/3D TiO2 nanostructures and control their density. Hollow nanostructures of TiO2 has been used as an ETL for PSCs with methylammonium lead iodide (MAPbI3) light‐absorbing layer and 2,2’,7,7’‐tetrakis‐(N,N di‐p‐methoxyphenyl‐amine)‐9,9’‐spirobifluorene (spiro‐MeOTAD) hole‐transporting layer (HTL). Here, we demonstrated hollow nanoflower morphology with a photocurrent density (JSC) of 21.05 mA cm−2, open circuit voltage (Voc) of 0.916 V, and fill factor (FF) of 0.66, leading to a power conversion efficiency (PCE) of 12.72 %, with an FTO/bl‐TiO2/etched TiO2–MAPbI3/spiro‐MeOTAD/Au device configuration. This secondary hydrothermal process provides a new approach for designing nanostructured metal oxides for highly efficient PSCs. More details can be found in the Full Paper by Dr. S. S. Mali et al. from Chonnam National University, Polymer Energy Materials Laboratory, Gwangju, South Korea on page 1775 in Issue 10, 2017 (DOI: 10.1002/ente.201700030). [ABSTRACT FROM AUTHOR]

[Display omitted] In this report, we demonstrate enlarged grain size (up to ∼3 μm) in ambient-stable black γ-phase CsPbI 2 Br thin films through the regulated addition of guanidinium iodide (GAI) as an effective volatile additive. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) measurements indicate the complete sublimation of GAI following annealing, with no inclusion inside the final γ-CsPbI 2 Br perovskite lattice. GAI is found to participate by retarding the cation–anion reaction via the Cs+ and GA+ cation-exchange process. We find that inorganic perovskite solar cells (IPSCs) devices made from (CsPbI 2 Br) 0.925 + 0.075 GAI and a phenyltrimethylammonium chloride (PTACl) passivation retain a solar-friendly band-gap of 1.91 eV and excellent device performance, with the best open-circuit voltage reaching as high as 1.34 V, with highly reproducible and stable photo conversion efficiencies of 16.88% (for 0.09 cm2) and 15.60% (large area 1 cm2) under ambient conditions. Photostability analysis further demonstrated negligible efficiency loss over 1000 h under continuous one-sun equivalent illumination, indicating GAI additive as a promising approach toward ambient stable, all-inorganic high-efficiency solar cells. [ABSTRACT FROM AUTHOR]

Development of ternary metal oxide (TMO) based electron transporting layer (ETL) for perovskite solar cell open a new approaches toward efficient a unique strategy for solid state dye-sensitized solar cells (ssDSSCs). In the present investigation, highly porous zinc tin oxide (Zn2SnO4) scaffold nanofibers has been synthesized by electrospinning technique and successfully used for methyl ammonium lead halide (CH3NH3PbI3) perovskite sensitized solid state solar cells. The fabricated optimized perovskite solar cell devices exhibited 7.38% power conversion efficiency (PCE) with open circuit voltage (VOC) 0.986 V, current density (JSC) = 12.68 mAcm-2 and fill factor (FF) 0.59 under AM 1.5 G sunlight (100 mWcm−2) which is higher than Zn2SnO4 nanoparticle (η = 2.52%) based perovskite solar cells. This improvement is achieved due to high porosity of Zn2SnO4 nanofibers and high crystallinity of the nanofibers synthesized at 700 °C. These results are remarkably higher than reported perovskite solar cells based on such type of ternary metal oxide ETLs. [ABSTRACT FROM AUTHOR]

Abstract: A simple solution method has been proposed that deals the specific impacts of solvent characteristics on the growth of zinc oxide (ZnO) nanoparticles. The aggregation of particles is a major drawback in the hydrothermal method, and it is suppressed by using a less polar reaction solvent. ZnO particles obtained from a lower polarity indexed reaction medium show a very strong UV band-edge emission with an almost negligible deep level emission when compared to ZnO particles isolated from the higher polarity index of the medium. For the application is concerned, highly dispersible ZnO nanomaterials are used as an active material for dye-sensitized solar cells (DSSC), due to their higher internal surface area. Additionally, the deposition of ZnO layers on commercially available GaN-based blue light emitting diodes (LEDs) is fabricated to improve the light extraction efficiency, without disturbing the basic structure of the LED. The layer thickness and light transmission at a specific wavelength are the major factors which can improve the light emission from LEDs. [Copyright &y& Elsevier]

Here, we have studied the influence of mixed halide methylammonium lead iodide (MAPbI 3) and MAPb(I 1-x Br x) 3 (x = 0.1) perovksite solar cells (PVSCs) based on based mp-TiO 2 ETL. In this work, the mixed halide MAPb(I 1-x Br x) 3 (x = 0.1) hybrid perovskite layer was deposited via solvent engineering process. Detailed solvent engineering process and its advantages has been discussed. The results revealed that, compared with single MAPbI 3 the mixed halide MAPb(I 1-x Br x) 3 hybrid perovskite based on mp-TiO 2 exhibits power conversion efficiency (PCE) of 14.92% with current-density (J SC) of 20.85 mAcm−2, open circuit voltage (V OC) of 1.056 V and FF of 0.68. Image 1 • Mixed halide efficient perovskite solar cells via solvent engineering process. • 14.92% PCE achieved for mixed halide efficient perovskite solar cells. • Controlled highly crystalline dense perovskite thin film. [ABSTRACT FROM AUTHOR]

• The ruthenium doped mesoporous TiO 2 synthesized via surface treatment. • Ruthenium doping enhance the optical and electronic properties of mesoporous TiO 2. • The efficiency and stability of mesoporous TiO 2 perovskite solar cell enhanced. • PSCs with 0.1 M Ru-TiO 2 show higher efficiency with negligible hysteresis. The electron transporting layer (ETL) plays a vital role in the power conversion efficiency (PCE) of perovskite solar cells (PSCs). We have demonstrated the synthesis of ruthenium doped mesoporous TiO 2 (Ru-TiO 2) and their utility as ETLs for PSCs. The doping effects of Ru4+ on the electronic and photovoltaic properties of mesoporous TiO 2 (mp-TiO 2) have been investigated as well. The highest PCE of 18.94% was obtained with 0.1 M Ru-TiO 2 PSCs exhibiting an open circuit voltage (V OC) of 1.128 V, current density (J SC) of 22.55 mA cm−2, and fill factor (FF) of 76.55%, whereas the conventional mesoporous PSCs showed PCE = 16.80%, V OC = 1.095 V, J SC = 21.50 mA cm−2, and FF = 70.01%. Note that the 0.1 M Ru-TiO 2 device shows high PCE with negligible hysteresis index, high reproducibility and more stability as compared to conventional mesoporous PSCs. [ABSTRACT FROM AUTHOR]

Highlights • MoO 3 is exploited in graphene/Si solar cells to induce p-doping in graphene. • Transparent conductive MoO 3 /Ag/MoO 3 DMD structure is investigated. • MAM multilayer coating improved the doping and device stability. • Sheet resistance as low as 10 Ω/□ is realized using MoO 3 /Ag/MoO 3. • Four-fold enhancement in the cell efficiency is demonstrated. Abstract Molybdenum trioxide (MoO 3) is one of the proven transition metal oxides to boost up the work function of graphene. In this letter, we report for the first time the use of MoO 3 based dielectric/metal/dielectric (DMD) multilayer coating to improve the photovoltaic performance of graphene/silicon solar cells. Solar cells employing transparent conductive MoO 3 /Ag/MoO 3 on graphene offered improved power conversion efficiency (PCE) by a factor of 4 compared to graphene only devices. This strategy appears advantageous not only to modulate the work function of graphene but also to reduce the device series resistance for better charge carrier extraction. [ABSTRACT FROM AUTHOR]

Obtaining long-term thermally stable via low-cost inorganic-hole extraction layer (i-HEL) is the best choice toward the commercialization of thermo-stable, low-cost perovskite solar cells (PSCs). In the present investigation, we have developed a simple method for p-type cesium incorporated NiO x (Cs:NiO x) an active interfacial layer between perovskite and cost-effective CuSCN i-HEL toward thermally stable PSCs. The Cs:NiO x nanoparticles were synthesized by the simple solution method and spin-coating on to perovskite layer, followed by CuSCN i-HEL deposition for mesoscopic regular (n-i-p) type PSCs. The developed method is not only protecting perovskite layer from polar diethyl sulfide solvent but also extract holes efficiently. The best efficiency based on Cs:NiO x /CuSCN double-i-HEL devices exhibited 19.24% with >95% thermal stability over 1000 h at 60 °C and >70% at 85 °C thermal air stability over 2000 h. Interestingly, NiO x /CuSCN and Cs:NiO x /CuSCN double-i-HEL-based devices are more stable than either conventional spiro-MeOTAD or single-i-HEL-based PSCs due to the perfect isolation of the perovskite layer from polar solvent. [ABSTRACT FROM AUTHOR]

Designing air-stable perovskite solar cells (PSCs) is a recent trend in low-cost photovoltaic technology. Metal oxide-based electron transporting layers (ETLs) and hole transporting layers (HTLs) have attracted tremendous attention in PSCs, because of their excellent air stability, high electron mobility, and optical transparency. Herein, we report a co-precipitation method for the synthesis of p-type nanoporous nickel oxide (np-NiOx) thin films as the HTL for inverted (p-i-n) PSCs. The best-performing p-i-n PSC having np-NiOx HTL, (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 (herein FAPbI 3 stands for formamidinium lead iodide and MAPbBr 3 stands for methylammonium lead bromide) perovskite and phenyl-C 61 -butyric acid methyl ester (PCBM)/ZnO ETL exhibited a 19.10% (±1%) power conversion efficiency (PCE) with a current density ( J SC ) of 22.76 mA cm −2 , open circuit voltage ( V OC ) of 1.076 V and fill factor (FF) of 0.78 under 1 sun (100 mW cm −2 ). Interestingly, the developed p-i-n PSCs based on p-type NiOx and n-type ZnO could retain >80% efficiency after 160 days, which is much higher than conventional PEDOT:PSS HTL-based PSCs. Our findings provide air-stable perovskite solar cells with high efficiency. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are coming with positive hopes for researchers to commercialize high-power conversion efficiency (PCE) and low-cost solar cells. Recently, NREL-certified record PCE of PSC is 22.1%, which is competing to silicon solar cells has been reported. However, PSC devices are environmentally sensitive leading to a rapid PCE degradation. Therefore, it is important to understand the impact of the role of various parameters to achieve highly stable PSC without compromising on its performance. This review contains an overview of a recent progress in PSC with respect to PCE, materials engineering, and stability. Energy level diagram of various perovskite materials, electron conducting materials (ECMs) and hole conducting materials (HCMs) constitute pivotal role in selecting their combinations. Hence we have added detailed energy level diagrams from which researcher can select best possible combination to achieve highest efficiency. An in-depth discussion on the types of PSCs based on thin film, mesoporous, n-i-p and p-i-n architectures fabricated by using different deposition techniques has been provided. In order to transfer this exciting achievement to industry level, it is necessary to understand degradation process at different conditions. A detailed discussion on the mechanism of recombination, instability in PSCs and achieved success has been incorporated to apprehend the step-wise developments in this field and to find possible pathways that limit their stability. [ABSTRACT FROM AUTHOR]

We investigated the thermal stability and electrical properties of nitrogen-doped reduced graphene oxide (NrGO)/ n –type Si solar cells. A NrGO layer was used as a transparent electrode as well as an electron-hole separation layer simultaneously. The effect of doping on the carbon and nitrogen bonding configurations in NrGO was investigated using X–ray photoelectron spectroscopy (XPS). The XPS data indicate that pyridinic–N is the dominant bonding configuration. This bonding configuration leads to a reduction in the power conversion efficiency and a decrease in the short circuit current. However, on being subjected to thermal oxidation, the NrGO/ n –type Si solar cells exhibit a smaller variation in series resistance compared to the undoped rGO/Si solar cells. Results of accelerated thermal tests suggest that nitrogen doping prevents re-oxidation of the reduced graphene oxide layer. [ABSTRACT FROM AUTHOR]

A cascade structure of TiO 2 /CdS/CdSe/ZnS quantum dot sensitized solar cell (QDSSC) is achieved to boost the photoconversion efficiency of TiO 2 /CdSe system by incorporating inner buffer layer of CdS. A sodium dodecyl sulfate (SDS) surfactant mediated TiO 2 nanorods assembly is prepared by a simple hydrothermal technique. The formation of CdS, CdSe and ZnS thin film over TiO 2 nanorods assembly as a photoanode is carried out by successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) techniques. Thus synthesized electrode materials are characterized by XRD, XPS, field emission scanning electron microscopy (FE-SEM), TEM, High resolution-TEM (HR-TEM), STEM-EDS mapping, Optical and solar cell performances. The results designate that the thin film of CdS and CdSe have efficiently covered exterior surfaces of TiO 2 nanorods assembly. The interfacial structure of TiO 2 /CdS/CdSe is also investigated and the growth interface is verified. A cautious evaluation between CdSe and CdS/CdSe sensitized cells tells that CdS helps to enhance the further growth of CdSe in the cascade electrodes and improves light harvesting. Under AM 1.5G illumination, the photoanodes show an improved power conversion efficiency of 2.56%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.80 mA cm −2 which is 18 times higher than that of a bare TiO 2 nanorods assembly. [ABSTRACT FROM AUTHOR]

In this article, single step synthesized few micrometer vertically aligned 1D rutile TiO 2 nanorods (TNR) were deposited directly onto FTO substrate by controlled hydrothermal route. Simple and cost-effective non-aqueous successive a ionic layer adsorption and reaction (SILAR) technique was adopted for the synthesis of cadmium sulfide (CdS) quantum dots (QDs) sensitization onto TNR. These CdS–TNR samples were further used for their quantum dot sensitization (QDSSC) performance in 0.5 M Na 2 S electrolyte. The CdS–TNR photoelectrode deposited at 40 SILAR cycles exhibits a photovoltaic performance with an open-circuit photovoltage ( V OC ) (0.606 V) and short-circuit photocurrent ( J SC ) (6.19 mA/cm 2 ). The highest power conversion efficiency of QDSCs is 1.87% has been achieved at relatively low nanorod length. Further, the transient and interface resistance properties were studied by open circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS) measurements. [ABSTRACT FROM AUTHOR]

The development of high efficiency Cu 2 ZnSnS 4 (CZTS) thin film solar cells depends on the synthesis of phase pure CZTS films. Due to the narrow phase window, it is difficult to prepare CZTS films with a pure kesterite phase (i.e., a film that lacks traces of detrimental secondary phases). For this, phase evolution of kesterite CZTS in films must be systematically studied. In the present study detailed phase evolution of kesterite CZTS via the sulfurization of stacked Cu/SnS 2 /ZnS precursor was examined. The phase evolution of kesterite CZTS was analyzed during the temperature-dependent sulfurization of stacked precursors. In addition to traditional X-ray diffraction and Raman analysis, transmission electron microscopy (TEM) characterization was used to study the phase evolution and trace locations of secondary phases in the sulfurized films. Furthermore, based on the experimental evidences the reaction pathways for the formation of CZTS kesterite phase and plausible phase evolution mechanism are proposed. [ABSTRACT FROM AUTHOR]

Abstract: We report planar heterojunction solar cell obtained by chemical vapor deposition (CVD) and hydrothermal technique. Copper phthalocyanine (CuPc) and titanium oxide (TiO2) were used as donor and acceptor materials respectively. The nanomorphologies like nanocorals, nanorods and nanoflowers were synthesized by the hydrothermal route and CuPc was deposited by CVD. The optical and compositional properties of TiO2/CuPc films were investigated by using UV–vis spectroscopy and X-ray photoelectron spectroscopy (XPS). Finally TiO2/CuPc devices were tested for their J–V properties. This approach would be quite useful for the fabrication of hybrid solar cells. The TiO2/CuPc device shows maximum photoconversion efficiency (η%) 0.41% for TiO2 nanoflower like morphology. [Copyright &y& Elsevier]

Abstract: Less-populated and well-isolated ZnO nanorods were prepared from a simple solution method by using polyethylene glycol (PEG) surfactant molecules. The structural and morphological information provided by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) demonstrated the high purity of the ZnO nanorods that were free from any unknown impurities. Furthermore, annealing treatment was used to increase the length of the ZnO nanorods further at an elevated temperature. This ZnO was used as a buffer layer for polymer solar cells (PSCs) in the device configuration of ITO/ PEDOT:PSS/P3HT-PCBM/ZnO/Ag, in which the Ag cathode was prepared by the inkjet printing method using silver ink. The present study discusses and compares the performance of the devices with and without the ZnO buffer layer. [Copyright &y& Elsevier]

In this investigation, the electrospun reduced graphene oxide-titanium oxide composite nanofibers as an electron transporting materials have been employed for the perovskite solar cells. The synthesized electron transporting materials have been used for the fabrication of mixed-cation lead mixed-halide (FAPbI 3) 0.85 (MAPbBr 3) 0.15 perovskite solar cells. The influence of reduced graphene oxide on titanium oxide nanofibers and their morphological and electronic properties have been investigated in detail. The optimized device having FTO/Bl-TiO 2 /rGO 4 –TiO 2 /(FAPbI 3) 0.85 (MAPbBr 3) 0.15 / s piro-MeOTAD/Au configuration exhibited a η = 17.66% power conversion efficiency with an open circuit voltage of 1.070 V, short circuit current density of 22.16 mAcm−2 and fill factor of 0.754. This obtained efficiency is much higher than that of mesoporous-titanium oxide (14.39%), pristine-titanium oxide nanofibers (15.82%) and other reduced graphene oxide-titanium oxide composite nanofibers based electron transporting materials. • Role of electron transporting materials in perovskite solar cells. • Influence of reduced graphene oxide on titanium oxide nanofibers by electrospinning. • Solvent engineering processed mixed halide mixed cation perovskite. • Larger grain size with reduced grain boundaries achieved. • The 17.66% power conversion efficiency achieved perovskite solar cells. [ABSTRACT FROM AUTHOR]