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• TiO 2 electron transport layer deposited by ALD at about 150 °C. • SnO 2 /PCBM double modifier at TiO 2 /perovskite interface. • Low-temperature processed perovskite solar cells with a PCE of 19.45%. • Enhanced performance compared to devices with solution processed TiO 2. Perovskite solar cells (PSCs) have attracted increasing attentions for their outstanding efficiency and simple fabrication process. However, the commonly used typical titanium dioxide (TiO 2) electron transport layer (ETL) requires a high-temperature treatment to crystallize. In this work, the low-temperature (150 °C) atomic layer deposition (ALD) processed TiO 2 ETL, and the SnO 2 /PCBM double interfacial modifier have been adopted to fabricate the high performance PSCs of ITO/ALD-TiO 2 /SnO 2 /PC 61 BM/MA 0.7 FA 0.3 PbI (3-x) Cl (x) /Spiro-OMeTAD/Ag. The measurement results show that the PSCs with ALD-TiO 2 ETL obtain the higher champion PCE of 19.45% than that of PSC with solution-TiO 2 ETLs (PCE = 18.64%), along with the obviously enhanced FF and V OC , as well as the better light stability and repeatability. And the transient photocurrent and photovoltage results demonstrate that the performance improvement origins from the enhanced charge transport and suppressed charge recombination. Therefore, the low-temperature ALD-TiO 2 ETL with suitable modification is a promising strategy to fabricate efficient PSCs and flexible devices. [ABSTRACT FROM AUTHOR]

Low temperature solution-processed C 60 exhibits favorable electron mobility and band alignment, thus it is widely used to modify the interfaces between perovskite film and electron transport layer (ETL) in n-i-p planar heterojunction perovskite solar cells (PSCs). However, when C 60 was used as an independent ETL, PSCs exhibit poor performance. Herein, We have modified solution-processed C 60 -based ETL with a solid-state ionic-liquid (1-ethyl-3-methylimidazolium iodide ([EMIM]I)). Using this interfacial modification method, we fabricated n-i-p planar heterojunction PSCs with optimized power conversion efficiency (PCE) of 15.09%, which was superior to that of PSCs based on unmodified C 60 ETL layer (12.11%). This work describes a novel method for low-temperature processing of efficient n-i-p PSCs. Image 1 • Modifying solution-processed C 60 -based ETL with a solid-state ionic-liquid in perovskite solar cell. • An efficiency of 15.09% shown in the solar cell with structure of FTO/IL/C 60 /CH 3 NH 3 PbI 3 /Sprio/Au. • Enhanced wettability and electron extraction exhibited in the IL/C 60 electron transport layers. [ABSTRACT FROM AUTHOR]

Carbon quantum dots derived from banana leaves by a simple hydrothermal process has been used as an electron transport layer to fabricate Organic Light Emitting Diodes. To the best of our knowledge, this is the first report of Carbon QD utilized as an electron transport layer inOLED. Devices with multilayered structureITO/PEDOT: PSS/PFO/CQD/LiF/Al are fabricated on indium tin oxide (ITO) coated glass substrates. Current‐Voltage (I−V) curves reveal that the turn‐on voltages are reduced from 8 V to 6 V as compared with pristine PFO device.Results show CQD as an ETL has enhanced the performance and efficiency of the OLEDs. [ABSTRACT FROM AUTHOR]

Nanostructured PANI–rGO–Y2O3 (PGY) nanocomposites with varying concentration of Y2O3 were synthesized via the oxidative polymerization process. The formation of PANI, GO, PANI–rGO and PGY nanocomposites were examined by FTIR, and XRD techniques and their structural properties were investigated by FESEM technique. The FESEM images displayed that the PANI and Y2O3 nanoparticles were uniformly decorated over GO sheets. The UV–Vis analysis exhibited optimized reduced band gap ~ 1.50 eV for 30% PGY nanocomposite. The optimized 30% PGY nanocomposite was attributed to four bands like violet, blue, green and orange bands, and color coordinates were located in the blue region. The electrical properties for optimized PGY 30% nanocomposite showed 107% enhancement in current density in comparison to pristine polyaniline and high dielectric constant with a low dielectric loss. The PGY 30% nanocomposite, illustrated reduced optical band gap, high carrier density, high dielectric constant, excellence rate of electron–hole recombination and enhanced carrier density that aimed to be a very suitable candidate for an electron transport layer in OLED devices. [ABSTRACT FROM AUTHOR]

To evaluate the chemical decomposition of the perovskite layer caused by the amount of hydroxyl groups remained on the interface of ZnO/perovskite films, ZnO films with different amount of hydroxyl groups are prepared by magnetron sputtering and spin-coating methods. The sputtered ZnO film contains the negligible hydroxyl groups because the hydrogen-free working gases of argon and oxygen are introduced during the sputtering process. In case of the optimized deposition condition under Ar/O 2 ratio of 1:4, the sputtered ZnO film shows larger grain size, bigger water contact angle, higher energy-level matching, better optical transmission, and higher conductivity in comparison with the spin-coated ZnO film. Moreover, the planar perovskite solar cells (PSCs) based on the sputtered ZnO electron transport layers (ETLs) yields an optimal power conversion efficiency of 17.22%, sharply outperforming that based on the spin-coated ZnO ETL (14.24%). More notably, the thermochemical stability of the device based on the sputtered ZnO ETL was also significantly improved. • ZnO films with different amounts of hydroxyl groups are prepared. • The thermal stability of the stack layers of ZnO/perovskite is investigated. • The PSC based on the sputtered ZnO ETL yields a maximum PCE of 17.22%. • The thermochemical stability of sputtered ETL-based device is improved. [ABSTRACT FROM AUTHOR]

Interfacial engineering is crucial to improve the photovoltaic performance of polymer solar cells (PSCs). In this study, we demonstrate efficient inverted non-fullerene PSCs with ZnO modified by nontoxic glycine (Gly) as the electron transport layer (ETL). With the modification of Gly, work function of the ETL interlayer was decreased from 4.11 eV for ZnO to 4.02 eV for ZnO/Gly, which effectively increased the built-in electric field and hence improved the electron extraction. Furthermore, the surface energy of interlayer was also reduced from 69.1 mJ/m2 for ZnO to 52.5 mJ/m2, which is beneficial for the enrichment of the acceptor at the interface and hence facilities the electron transport and collection at cathode electrode. Therefore, the device based on PM6:IT-4F with ZnO/Gly as ETL exhibited a remarkably enhanced power conversion efficiency (PCE) of 14.0% relative to 12.9% for the control device with ZnO ETL, indicating a ∼9% increase of the PCE with the simple molecular modification of the ETL. Meanwhile, this strategy can also be successfully applied to other non-fullerene and fullerene based inverted PSCs. Our work provides an effective approach to modify ZnO for high performance PSCs. Nontoxic glycine modified ZnO was used as the electron transport layer (ETL), which shows fewer defects, lower work function and lower surface energy, and therefore promote the photovoltaic performance of the inverted non-fullerene polymer solar cells. Image 1 • Nontoxic glycine modified ZnO is used as the electron transport layer in inverted non-fullerene polymer solar cells (PSCs). • The glycine modified ZnO interlayer shows lower work function, fewer defects and lower surface energy. • With the glycine modified ZnO interlayer, higher efficiencies are obtained in the inverted non-fullerene PSCs. [ABSTRACT FROM AUTHOR]

The electron transport layer plays a vital function in extracting and transporting photogenerated electrons, modifying the interface, aligning the interfacial energy level and minimizing the charge recombination in perovskite solar cells. This review summarizes the recent research progress on electron transport materials of metal oxides, organic molecules and multilayers. The doped metal oxides as electron transport materials in regular perovskite solar cells show improved device performance relative to their non-doped counterpart due to enhanced electron mobility and energy level alignment. The non-fullerene organic electron transport materials with better electron mobility and tunable energy level alignment need to be further designed and developed despite their advantages of mechanical flexibility and wide range tunability. The multilayer electron transport materials are suggested to be an important direction of research for efficient and stable perovskite solar cells because of their favorable synergistic interaction. [ABSTRACT FROM AUTHOR]

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We demonstrate a highly efficient red cadmium‐free quantum dot light‐emitting diode (QLED) comprising inverted structure and ZnO:Mg nanoparticles as an electron transport layer. Fabricated QLED reveals maximum external quantum efficiency of 4.46% and more than two‐fold increase in efficiency (10.17%) after aging for several days. [ABSTRACT FROM AUTHOR]

The ternary nanocomposite comprised of PPY–PANI (polypyrrole–polyaniline) copolymer and zinc oxide (ZnO), synthesized by implying chemical oxidative polymerization of pyrrole monomer in presence of ammonium persulfate as oxidant with varying ZnO concentrations. The shifting of bands and their corresponding change in nano-strain of as-prepared PPY–PANI–ZnO nanocomposite of varying concentration was confirmed by the Fourier transform inferred spectroscopy (FTIR). The surface morphological images of PPY–PANI–ZnO nanocomposites revealed the nano-flake like structure attributed to the embodiment of ZnO and increase in agglomeration was detected with the increasing concentration of ZnO. The optimized reduction in band gap up to ~ 1.02 eV and red-shift of absorption edge of ZnO in visible region side was detected for 10% PPY–PANI–ZnO nanocomposite. The relatively slow decay component and higher non radiative electron–hole recombination rate showed the better electron transport properties with chromaticity in ideal blue region for 10% PPY–PANI–ZnO nanocomposite. The higher current density ~ 7.95 A/cm2, high dielectric constant ~ 1960 at 373 K, high reduction potential ~ + 0.687 V with high specific capacitance (~ 436.14 F/g) at 10 mV s−1 and better thermal firmness was observed for 10% PPY–PANI–ZnO nanocomposite. The relatively high discharge time ~ 2600 s and high power density with meagre loss in energy density at high current density was also observed for 10% PPY–PANI–ZnO nanocomposite. These robust properties confirmed that the proposed 10% PPY–PANI–ZnO nanocomposite could be employed as electron transporting material for OLEDs as well as for high performance and efficient supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract Two dimensional rGO was decorated over circular-bipyramidal structure of PPY-TiO 2 by chemical oxidative polymerization of pyrrole monomer. The structural analysis of PPY, GO, TiO 2 , PPY-TiO 2 and PPY-TiO 2 -rGO nanocomposite was observed by XRD, FESEM and TEM analysis. Inflated non-radiative electron-hole recombination rate and lower value of decay time with better thermal stability were observed for PPY-TiO 2 -rGO nanocomposite. Enhanced current density (~ 300%), optimized low band gap (~ 1.32 eV), high dielectric constant and high specific surface area were also observed for ternary nanocomposite. The PPY-TiO 2 -rGO electrode also manifested the high specific capacitance value (~ 1171 F/g) and high discharge time (~ 3450 s) with high electrochemical reduction potential (~ +0.610 V). These increased rates of non-radiative recombination, reduced band gap, enhanced conductivity and thermal stability, high values of dielectric constant, improved electrochemical reduction potential, augmented specific capacitance, high discharge time and power density (~ 799.74 W/kg) with scant loss in energy density at high current density proposed that, PPY-TiO 2 -rGO nanocomposite can be employed as electron transport layer (ETL) material in OLED devices and supercapacitor electrode material. [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 Metal oxide electron transport layers play a crucial role on the extraction and transportation of charge carriers in organic-inorganic hybrid perovskite solar cells (PSCs). However, generally, fabrication of conductive metal oxide thin films requires high temperature annealing which is not compatible with roll to roll fabrication. It has been observed that a low temperature fabricated pristine metal oxide film exhibited low electrical conductivity, which has still prohibited to achieve high performance of device. Therefore, a low amount of metal doping within the pristine metal oxide films followed by low temperature thermal annealing is an effective approach to improve the electrical properties of the metal oxide thin films, and, thus, leading the higher performance of PSCs. Herein, we have developed a low temperature (180 °C) solution processed Molybdenum (Mo) doped SnO 2 (SnO 2 :Mo) as an efficient electron transport layer (ETL) for the fabrication of planer PSCs. The electrical conductivity of pristine film was significantly enhanced after the incorporation of a small amount of Mo dopant within the neat SnO 2 film, which could facilitate fast transportation of photo-generated charge carriers. Moreover, due to n-type Mo doping, Fermi level of resulting film was slightly shifted upwards, which could diminish charge recombination and, hence, improved the photovoltaic performance. The power conversion efficiency (PCE) for pristine SnO 2 and SnO 2 :Mo based PSCs was found to be 8.47% and 10.52%, respectively, when ETL and perovskite absorber films were processed in ambient conditions with the relative humidity range of 65%–75%. Compared to pristine SnO 2 , SnO 2 :Mo based PSC exhibited higher performance, which was attributed to the enhanced electrical properties of the resulting doped ETL thin film. Our results indicated that low temperature (180 °C) solution processed SnO 2 :Mo is a promising ETL for cost effective roll to roll fabrication of PSC. Graphical abstract Image 1 Highlights • Low temperature (180℃) solution processed Mo doped SnO 2 (SnO 2 :Mo) film as an efficient electron transport layer. • The XPS and SEM with elemental mapping proved the presence of Mo doping in the resulting film. • An optimal concentration of 1.0 mol% SnO 2 :Mo based PSC exhibited highest PCE of 10.52% under ambient conditions. [ABSTRACT FROM AUTHOR]

Abstract Optimizing electron transport layer (ETL) is a key issue to guarantee the performance of polymer solar cells (PSCs). In this work, by passivating ZnO with a naphthalimide-Schiff base (NS) as ETL, the inverted PSCs with polythieno[3,4- b ]- thiophene- co -benzodithiophene (PTB7): [6, 6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) as the light harvesting layer (LHL) exhibited enhanced device performance. Studies demonstrated that the NS introduction passivates the surface defects of ZnO thus suppressing exciton quenching, resulting in enhanced exciton dissociation, efficient charge carrier collection and reduced loss of charge recombination, and thereby giving high power conversion efficiency (PCE). While the PCE of the inverted PSCs with pure ZnO ETL is 7.34%, that of the devices with NS passivated ZnO (NS-ZnO) ETL shows an enhanced PCE of 8.20% (∼11.7% improvement). More importantly, the NS-ZnO can be facilely obtained by adding NS into ZnO precursor, suggesting a simple and efficient way to enhance the PSCs performance. Graphical abstract This work identifies naphthalimide-Schiff passivated ZnO electron transport layer would dramatically improve the performance of inverted polymer solar cells. Image 1088 Highlights • A newly naphthalimide-Schiff base NS was synthesized. • Formation of composite ETL was obtained by adding NS in ZnO precursor. • Polymer solar cells based NS passivated ZnO ETL shows an enhanced PCE of 8.20%. • Introduction of NS optimized exciton dissociation, charge carrier collection and charge recombination. [ABSTRACT FROM AUTHOR]

Highlights • Hf-In-ZnO (HIZO) as electron transport Layer for inverted organic solar cells (iOSC). • Twice lifetime of encapsulated HIZO-iOSC vs. currently used PFN-iOSC. • Reduced S-shape deformation in the JV curves of HIZO-iOSC vs. PFN-iOSC. Abstract In this study, we report the use of Hafnium-Indium-Zinc-Oxide (HIZO) as electron transport layer (ETL) in inverted organic solar cells (iOSCs) using a bulk heterojunction of Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) and [6,6]-phenyl C71 butyric acid methyl ester (PC 70 BM) as active layer. The absorption spectrum and performance parameters obtained are compared to those obtained for similar iOSCs where the ETL was poly [(9,9-bis (30- (N,N-dimethylamino) propyl) -2,7-fluorene) -alt-2,7- (9,9-dioctylfluorene)] (PFN). Initially, devices showed the S-shaped current–voltage curve that has been modeled using a three-diode equivalent circuit model. This phenomenon can be removed by repeating electrical sweep-cycles under illumination. The degradation under nitrogen atmosphere and under encapsulation was also analyzed and compared with the degradation of the iOSCs using PFN. It was observed that the degradation of encapsulated HIZO-iOSC was twice slower than that of PFN-iOSCs. This increase in stability can be attributed to the Hf atoms, which have a stronger thermodynamic tendency to form metal oxides, suppressing the dissociation of HIZO. [ABSTRACT FROM AUTHOR]

Abstract In this study, we realized an inverted polymer solar cell by depositing Al-doped ZnO (AZO) through room temperature radio-frequency magnetron sputtering as an electron transport layer (ETL) between an organic PTB7 and PC 71 BM mixture active layer and indium tin oxide (ITO) transparent electrode. The crystal structure of the AZO thin films changed as the Ar gas pressure was varied. X-ray diffraction showed that the highest crystallinity was obtained at 70 mTorr. Further experiments were carried out to determine the optimum thickness. An AZO film deposited on a glass substrate with a thickness of 100 nm had an average visible-light transmittance of 83.3% and an electrical resistivity of 6.6 × 10−3 Ω·cm. The power conversion efficiency (PCE) showed no significant difference with regard to thickness, and ranged from of 7% to 8%. The 100-nm AZO thin film had the highest PCE of 7.87%, which is approximately 90% higher than that of the sample without an ETL. Graphical abstract Image 1 Highlights • AZO thin films were optimized by RF magnetron sputtering. • AZO thin films with high crystallinity were obtained at room temperature. • AZO thin films were applied for PTB7:PC 71 BM blend-based PSC as an ETL layer. • Thickness dependent PCE was analyzed by measuring the J-V curve of the PSCs. • The PSC with the 100-nm AZO thin film had highest PCE of 7.87%. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The charge carrier mobility can be effectively improved by doping Ag into TiO 2 electron transport layer. • Ag-doped TiO 2 electron transport layer can reduce the J-V hysteresis. • The PCE of perovskite solar cell based on 1.00 mol% Ag-doped TiO 2 electron transport layer reached to 17.7%. Abstract Organic-inorganic hybrid perovskite solar cells (PSCs), a superstar of photovoltaic devices, have attracted people's attention owing to their adjustable energy band gap value, extremely high absorption coefficient, long charge carrier diffusion length, and dramatically high power conversion efficiency. In recent years, researchers have tried hard to explore new strategies in order to obtain better optical characteristics. Metal ion-doped electron transport layer (ETL) is a convenient way to improve the optical properties of PSCs. By this method, the conduction band and valence band position can be changed. This can lead to the carriers can effectively transport, and the charge recombination between ETL and absorber layer be reduced. In our study, we have enhanced the photovoltaic performance and the hysteresis behavior of the device by using various concentrations of mesoscopic Ag-doped TiO 2 (meso-Ag:TiO 2) as the ETL. We also systematically discussed the surface morphology, the charge carrier dynamic, the electron mobility, and the electrical conductivity for our devices. Finally, by optimizing the parameters of PSCs and the energy band alignment between perovskite absorber layer and ETL, the power conversion efficiency (PCE) of the champion device with 1.00 mol% meso-Ag:TiO 2 ETL reached as high as 17.7%. [ABSTRACT FROM AUTHOR]

Abstract Vertical ZnO nanorod arrays were synthesized by a polymer template method and modified by TiO 2 shell via a sol-gel method. The core-shell structure of ZnO-TiO 2 nanorod arrays was used as an electron transport layer (ETL) of perovskite solar cells (PSCs) and the length of the nanorod arrays was controlled by changing the hydrothermal growth time. The photovoltaic performance of the PSC prepared in ambient atmosphere was found to be crucially dependent on the length of ZnO-TiO 2 nanorod arrays. ZnO-TiO 2 nanorod arrays with a suitable length enabled complete infiltration of CH 3 NH 3 PbI 3 perovskite into nanorod arrays and an increasement of carrier lifetime, eventually resulting in better cell performance. The PSC based on ZnO-TiO 2 nanorod arrays with the length of 600 nm shows a power conversion efficiency of 10.24% under ambient air (RH~40%, 25 °C), which is higher than the mean level of previous report. Meanwhile, the PCE of the unencapsulated device based on ZnO-TiO 2 nanorod arrays retains 80% of the initial efficiency after 7 days in ambient atmosphere. This work provides the potential application of ZnO-TiO 2 nanorod arrays with a suitable length as an effective ETL of efficient and stable all-solid-state PSCs. [ABSTRACT FROM AUTHOR]

Abstract Three CN modified terdibenzofuran compounds, [2,2':8′,2″-terdibenzo[b,d]furan]-8,8″-dicarbonitrile (2CN2TDBF), [2,4':6′,2″-terdibenzo[b,d]furan]-8,8″-dicarbonitrile (2CN4TDBF), and [4,2':8′,4″-terdibenzo[b,d]furan]-6,6″-dicarbonitrile (4CN2TDBF), were synthesized as exciton blocking materials of blue phosphorescent organic light-emitting diodes (PhOLEDs) to understand the effect of interconnect position between dibenzofuran units and CN substitution positions in the dibenzofuran. Both the interconnect position and CN substitution position affected the lowest unoccupied molecular orbital (LUMO) of the exciton blocking materials. The LUMO stabilization effect was significantly noted in the 4CN2TDBF exciton blocking material, while it was marginal in the 2CN4TDBF exciton blocking material. The LUMO of 2CN2TDBF was in between that of 4CN2TDBF and that of 2CN4TDBF. Therefore, the LUMO level management of the CN modified terdibenzofuran compounds was effectively accomplished by engineering the interconnect position of dibenzofuran and CN modification position. Highlights • CN modified dibenzofuran as an electron transport unit of hole blocking materials. • High triplet energy electron transport materials derived from trisdibenzofuran derivatives. • Energy level management of trisdibenzofuran derivatives by controlling interconnect position and CN position. [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 Tin based perovskite FASnI 3 is an excellent absorber material to achieve high power conversion efficiency (PCE) at low cost for photovoltaic utilities. It is essential to realize how solar cell parameters like doping concentration (N A), defect density (N t), band gap (E g), operating temperature and thickness influence the performance of photovoltaic device. In this study we have reported the perovskite solar cell (PSC) model with novel inverted architecture Glass / FTO / NiO / FASnI 3 /C 60 /Au using device simulation tool. FASnI 3 is feasible material because of its narrower band gap and broad absorption spectrum as compare to its lead based counterpart. By optimized parameters we obtained power conversion efficiency (PCE) 9.99%, open circuit voltage (V OC) 0.97 V, short circuit current density (J SC) 25.95 mA/cm2 and fill factor (FF) 80.85% which are much improved parameters for FASnI 3 as compare to available in literature. This model allows researchers to characterize fundamental solar cell parameters to obtain high performance of photovoltaic devices. [ABSTRACT FROM AUTHOR]

Abstract A novel ternary hybrid material zinc oxide & polyethyleneimine ethoxylated: reduced graphene oxide (ZnO&PEIE:RGO) is fabricated, and then used as electron transport layer (ETL) to improve the performance of inverted polymer solar cells (iPSCs). Compared with the pure ZnO as ETL, the power conversion efficiency (PCE) of iPSCs based on P3HT:PCBM blend system with ZnO&PEIE:RGO as ETL is efficiently improved from 3.00% to 3.83%. The addition of RGO increases the conductivity of ZnO, and the addition of PEIE not only passivates the surface of ZnO nanoparticles to reduce its surface defects, but also prevents the aggregation of the precursor dispersion of ZnO:RGO. Moreover, the performance of the PTB7:PCBM based iPSCs with ZnO&PEIE:RGO as ETL is also improved from 6.91% to 8.87% compared with that of the device with pure ZnO as ETL. Interestingly, devices with ZnO&PEIE:RGO also exhibit enhanced lifetimes devices with ZnO, which still retain up to 63% of their original PCE after stored for 30 days without any encapsulation in air. Consequently, this novel ternary hybrid material ZnO&PEIE:RGO is a promising ETL material for PSCs. Graphical abstract Image 1 Highlights • A novel ZnO&PEIE:RGO nanocomposite is prepared by an in-situ synthesis method. • The addition of RGO improves the electrical conductivity of hybrid ETL. • The mixture of PEIE passivates the surface defects of hybrid ETL. • The performance of the iPSCs with ZnO&PEIE:RGO as ETL is obviously improved. • More interesting, the device with ZnO&PEIE:RGO as ETL has a long-term stability. [ABSTRACT FROM AUTHOR]

Abstract We present a solution-processed flexible organic photodiode (f-OPD) with a bulk heterojunction (BHJ) structure based on a blend of poly (3-hexylthiophene-2,5-diyl) and 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C 61 (P3HT:PCBM). We used Cs 2 CO 3 -doped polyethyleneimine ethoxylated (d-PEIE) as the electron transport layer (ETL) material, which significantly improved the electron injection properties of the f-OPD. Compared with f-OPDs with conventional ETL materials such as Cs 2 CO 3 , the external quantum efficiency (EQE) of the d-PEIE-based f-OPD was highly improved. Analytical results showed that the d-PEIE reduced the work function of the cathode, thereby facilitating the efficiency of electron injection from the active layer (AL) to the cathode of the f-OPD. In addition, after 10,000 cycles of tensile bending at a bending radius of 5 mm, the normalized I D variation (I D / I D0) in the d-PEIE-based f-OPD remained above 90%, indicating an excellent device bending stability. Finally, f-OPD-based luminescent oxygen (O 2) sensors were successfully fabricated consisting of a photoluminescent O 2 sensing film, a light source, and an f-OPD. The O 2 sensors based on d-PEIE-based f-OPDs showed the highest photocurrent and O 2 sensitivity in relation to the O 2 concentration compared with O 2 sensors based on f-OPDs with conventional ETL materials. Graphical abstract Image 1 Highlights • The solution processed P3HT:PCBM based flexible OPDs (f-OPD) by Cs 2 CO 3 -doped polyethyleneimine ethoxylated (d-PEIE) as the ETL material showed significantly improved optoelectronic and mechanical properties. • The d-PEIE based f-OPD reduced the work function of cathode facilitating the efficient electron injection from the active layer to the cathode of the f-OPDs. • The d-PEIE enhanced the adhesion between the AL and cathode, which improved the mechanical stability of the f-OPDs. [ABSTRACT FROM AUTHOR]

Abstract Collection of photo-generated charge carriers is of significance in organic photovoltaic devices. Herein, we focus on systematically exploring the effective methods to improve the charge collection efficiency in organic solar cells based on PBDB-T: ITIC. In the active layer, we observe that the energy level bending at the interface of acceptor/donor is influential to the recombination of charge carriers. For extracting electrons efficiently, we propose that using SnO 2 instead of ZnO as the electron conducting layer is advantageous in improving short-circuit current (J sc), power conversion efficiency (PCE), and particularly stability. To unveil the dynamics of hole collection, we use different metals as the anode and find out that enlarging the work function of the anode close to the highest occupied molecular orbital (HOMO) of the donor is beneficial for enhancing the open-circuit voltage (V oc), J sc , fill factor (FF) and thus PCE. The optimized device delivers a PCE of 10.77%. Insights on how to efficiently extract photo-generated charge carriers are elaborated systematically. Graphical abstract Image 1 Highlights • Using SnO 2 as ETL could enhance extracting electrons efficiency. • Enlarging the work function of the anode improves the performance. • Insights on how to efficiently extract charge carriers are elaborated. [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]

• MoSe 2 were prepared by hydrothermal, ultrasonic and microwave irradiation methods. • Hydrothermal method influences the crystalline size, morphology, band gap and surface area. • MoSe 2 :H served as electron transport layer affecting the photovoltaic performance. • MoSe 2 :H achieved higher efficiency of 8.47% than MoSe 2 :U,7.42% and MoSe 2 :U,6.74%. The present investigation utilizes three distinct techniques, including hydrothermal (MoSe 2 :H), ultrasonic (MoSe 2 :U) and microwave irradiation methods (MoSe 2 :M), to synthesise nanostructures of molybdenum diselenide (MoSe 2). Several analytical techniques were used to evaluate the effects of synthesis method on the physicochemical properties of MoSe 2. Hydrothermal synthesis of MoSe 2 enhances the performance of perovskite solar cells (PSCs) by strengthening the electron transport layer. The findings show that the hydrothermal method enhances the crystalline size, morphology and narrowed band gap, and increases the surface area, ultimately influencing photovoltaic performance. The efficiency of MoSe 2 PSCs fabricated through the hydrothermal method is 8.47% (MoSe 2 :H), surpassing the efficiency of ultrasonic (MoSe 2 :U,7.42%) and microwave irradiation methods (MoSe 2 :U,6.74%). [ABSTRACT FROM AUTHOR]

2D Ag-ZIF interlayer plays a dual-passivation effect in terms of passivating both the oxygen vacancies on the SnO 2 and the uncoordinated Pb2+ at the bottom of the perovskite layer. [Display omitted] • 2D Ag-ZIFs are synthesized by a solvent modulated strategy. • 2D Ag-ZIF interlayer passivates the defects at perovskite/SnO 2 interface. • PSCs based on 2D Ag-ZIFs modified SnO 2 yield the champion PCE of 21.25%. • PSCs with 2D Ag-ZIFs exhibit enhanced UV and environmental stability. Despite the fact that perovskite solar cells (PSCs) have made rapid progress as a promising photovoltaic technology, defect management at the interface between the electron transport layer (ETL) and perovskite layer remains critical to significantly reduce energy loss of devices. Therefore, developing a robust and effective interlayer is imperative. Herein, 2D Ag doped ZIF-67 (Ag-ZIF) is designed by a solvent modulated strategy based on mixed N, N-dimethylformamide and ethanol, and further applied as an interfacial modifier in PSCs. Since the exposed dimethylimidazole ligands carried by Ag-ZIF and the metal ions, the oxygen vacancies on the SnO 2 surface and the uncoordinated Pb2+ and halogen ions at the bottom of the perovskite layer could be passivated effectively. Thus, suppressed non-radiative recombination and accelerated electron transport are achieved. Meanwhile, the robust framework and ultraviolet (UV)-resistant ability of Ag-ZIF could regulate the crystallization of perovskite film and prevent device from UV degradation. Consequently, the efficiency of PSC is remarkably boosted from 18.49% to 21.25% in accompany with enhanced UV and environmental stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • TSAPS effectively inhibited the oxygen vacancy on SnO 2 surface, which leads to oxygen vacancy decreased from 68.40% to 45.26%. • The unencapsulated SnO 2 /TSAPS-based flexible device can maintain 84% of its initial efficiency after 3000 bending cycles, while the control one sharply decrease to 9%. • Surface and bulk defects in perovskite have been greatly restrained after TSAPS modification, resulting in enhanced PCE from 15.22% to 18.63% for flexible PSCs. Flexible perovskite solar cells (F-PSCs) are currently a research hotspot due to their lightweight, solution processability, and low cost. However, oxygen vacancies in SnO 2 would deteriorate the crystallization of perovskite, especially in F-PSCs due to the low temperature of SnO 2 preparation with flexible substrates, thus inducing poor performance and decreased bending resistance. Here, trichlorobenzene sulfonic acid potassium salt (TSAPS) is used as an effective oxygen vacancy restrain additive on the SnO 2 surface for F-PSCs. The oxygen vacancies are reduced from 68.40% to 45.26% after TSAPS modification. Meanwhile, the interfacial defects are suppressed by the synergistic passivation of individual ions in TSAPS, thus the carrier extraction and transportation are effectively improved. As a result, the PCE of the F-PSCs greatly increased from 15.22% to 18.63%. In addition, the unencapsulated SnO 2 /TSAPS-based flexible device can maintain 84% of its initial efficiency after 3000 bending cycles, exhibiting superior mechanical stability, while the control one decreased to only 9%. This work demonstrates a dependable method for improving the quality of the interface between the ETL and perovskite layer, resulting in enhanced bending resistance and performance for flexible PSCs. [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]

In perovskite solar cells (PSCs), tin oxide (SnO 2) has been widely used as the electron transport layer (ETL) due to its wide bandgap and high electron mobility. Among the various deposition methods, radio frequency (RF) sputtering offers many advantages for the commercialization of PSCs fabrication. However, conventional PSCs with sputtered SnO 2 are subject to severe hysteresis, which occurs owing to defect sites at the ETL-perovskite interface. Further, these defect sites induce non-radiative carrier recombination, causing a decrease in open-circuit voltage and device fill factor. Herein, the surface of RF-sputtered SnO 2 was passivated with potassium chloride (KCl) aqueous solution. Through this treatment, it was possible to passivate the defect sites at the interface and change the band alignment for effective electron transport. Thus, a decrease in the trap density of the perovskite led to an increase in efficiency (from 20.9% to 21.9%) and reduction in the hysteresis (from 10.5% to 2.7%) of the PSC. Hence, the KCl passivation process of RF-sputtered SnO 2 could be adopted to manufacture hysteresis-free high-efficiency PSCs. • RF-sputtered SnO 2 could be easily passivated by potassium chloride aqueous solution. • Hysteresis of perovskite solar cells is eliminated by passivating the SnO 2 and reducing the trap density of perovskite. • The highest efficiency (21.9%) is obtained among perovskite solar cells based on sputtered SnO 2. [ABSTRACT FROM AUTHOR]

Reducing the sintering temperature and time of mesoporous titanium dioxide (m-TiO 2) from the standard thermal approach of baking at 500 °C for 1 h is an important step for employment of mesoscopic perovskite solar cells (PSCs). We present a robust method based on atmospheric pressure ambient air plasma of the diffuse coplanar surface barrier discharge (DCSBD) for sintering of m-TiO 2 in 2.5 min at 70 °C. When implemented in PSCs as an electron transport layer an efficiency of (15.8 ± 1.0) % was achieved, which is on the same level as a standard thermal approach. The organic moieties which hinder the perovskite infiltration into the porous structure were removed to a similar extent as the thermal sintering. The approach does not affect the conduction band alignment with the perovskite absorber and an appropriate energy offset is preserved. • Plasma sintering of mesoporous titania electron transport layer operates in open air at atmospheric pressure. • Within just 2.5 min at 70 °C the same results were obtained as after 1 h at 500 °C of standard thermal sintering. • Perovskite solar cells with plasma-sintered mesoporous titania reached 15.8% power conversion efficiency. [ABSTRACT FROM AUTHOR]

[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is extensively applied as the electron transport layer (ETL) in CH 3 NH 3 PbI 3 -based solar cells, but it is expensive and hygroscopic in the atmosphere. ZnO is cheap and air-stable, but the reaction between ZnO and CH 3 NH 3 PbI 3 generally causes the degradation of the latter. In this paper, ZnO-embedded PCBM (ZPCBM) ETLs were prepared by spin-coating the ZnO nanograin dispersion mixed with the PCBM precursor solution in an optimal volume ratio of 1:3. Embedded ZnO nanograins enhance the electron extraction ability and the hydrophobicity of the PCBM matrix, while the amorphous PCBM matrix reduces the direct contact between ZnO nanograins and the CH 3 NH 3 PbI 3 absorption layer, thus depressing the reaction between them. As a result, the un-encapsulated ZPCBM/CH 3 NH 3 PbI 3 /NiO solar cell exhibits a high PCE of 19.21% and an open circuit voltage of 1.07 V. After exposure to the atmosphere for 1008 h, it retains 90% of the initial PCE, showing a greatly improved air stability compared with CH 3 NH 3 PbI 3 solar cells with the PCBM or ZnO ETL. [ABSTRACT FROM AUTHOR]

This work reports on the synthesis of polymeric PANI-rGO-WS 2 (PGW) nanocomposites were synthesized with varying concentrations of WS 2 via chemical oxidative polymerization. FESEM images elucidated that the surface morphology of PGW3 carried a structure comprising of PANI nanofibers embedded on the top of the overlapped rGO and WS 2 nanosheets. XRD and FTIR spectroscopy showed the molecular interaction among the constituents and affirmed the formation of PGW nanocomposite. UV–Vis. spectroscopy revealed the absorption of light in visible region with the for PGW3 nanocomposite. Photoluminescence spectroscopy showed light absorption in blue color region with excellent color purity. TGA showed the optimized PGW3 nanocomposite has inflated thermal stability. Current density for PGW3 nanocomposite was examined using J-V characteristic curve and found 96% higher than polyaniline. The increased conductivity and high electron-hole recombination rate attributed to the formation of enhanced charge transport network in PGW3 nanocomposite. These results evinced the optimized PGW3 nanocomposite as an ETL for OLED applications. • In-situ oxidative polymerization method is used to synthesize PANI-rGO-WS 2 nanocomposites with varying concentration of WS 2. • The band gap of optimized PGW3 nanocomposite is determined to be 1.95 eV with a crystallite size of 6.54 nm. • PGW3 nanocomposite showed blue emission at 483 nm range with 39% color purity. • The mobility of charge carriers was also calculated using hall effect measurement and found to be 2.707 m2V−1s−1 • The current density for the optimized PGW3 was evaluated ∼3.45 Acm−2 using J-V characteristic curve. [ABSTRACT FROM AUTHOR]

• The study focused on modeling and analyzing novel CZTS-based thin film solar cells using the SCAPS environment. • Twenty ETL and fourteen HTL layers were applied to CZTS based device structure CZTS / C d O / Z n O. • A total of 280 device structures were simulated and analyzed using SCAPS. • Among these structures, 49 exhibited power conversion efficiencies (PCE) ranging from 11.01% to 21.40%. • From device structure, SnS/CZTS/CdSe/ZnO, a PCE greater than 21.40% was achieved. This paper presents a thorough numerical investigation of copper zinc tin sulfide (CZTS)-based solar cells utilizing the SCAPS-1D simulation tool. In light of the scarcity of indium and gallium, CZTS is explored as a promising alternative absorber material. The study encompasses an extensive array of 280 device simulations, including a systematic optimization process targeting enhanced power conversion efficiency (PCE). Notably, this iterative optimization procedure results in a notable PCE increase from 11.01% to 14.24%. By delving into the realm of electron transport layer (ETL) materials, the integration of a CdO layer culminates in a significant PCE milestone of 15.71%, and a new structure was extrapolated from this step Back contact/CZTS/CdO/ZnO. Furthermore, an exploration involving 172 diverse configurations incorporating various hole transport layer (HTL) materials unveils a remarkable peak PCE of 21.14% (Back contact/SnS/CZTS/CdSe/ZnO). These findings provide valuable insights and directives for the advancement and optimization of CZTS-based solar cells. [ABSTRACT FROM AUTHOR]

• A high-efficiency SLG/Mo/Cu 2 MnSnS 4 /SnS 2 /ZnMgO/ZnO:Al/Pt solar cell is proposed. • Sn-/Zn-based (oxide) buffer and window layers of the emerging CMTS solar cell are optimized to achieve the best output using SCAPS-1D. • The V OC , J SC , FF, and PCE of the CMTS solar cell are simulated as 1.236 V, 23.69 mA/cm2, 85.49%, and 25.03%, respectively. • The impact of different properties of each active layer of optimized structures, such as bandgap, layer thickness, carrier concentration, etc., are analyzed. Copper Manganese Tin Sulfide, Cu 2 MnSnS 4 (CMTS), has emerged as a potential candidate for cost-competitive, eco-friendly single- or multiple p-n junction kesterite quaternary photovoltaics (PVs) due to its distinct optical and electrical properties, with earth-abundant as well as non-toxic constituents. In this article, Cu 2 MnSnS 4 absorber-based heterostructures with ZnMgO, WS 2 , SnO 2, CdS electron transport (window) and SnS 2 , ZnSe, ZnSnO, Zn(O,S) buffer layers have been investigated by executing a systematic study and proposing the mostly efficient device structures containing the favourable band alignment using the SCAPS-1D simulator. Initially, an effective buffer and electron transport (window) layers have been optimized from Al:ZnO/window (ZnMgO, WS 2 , SnS 2, or CdS)/buffer (SnS 2 , ZnSe, ZnSnO, Zn(O,S))/Cu 2 MnSnS 4 /Pt structures. Subsequently, the impact of different properties of each active layer of optimized structures, such as bandgap, layer thickness, carrier concentration, bulk and interface defect densities, and working temperature, was determined by measuring PV parameters and corresponding quantum efficiency. The present study exhibited the maximum photocurrent, J SC of 23.69 mA/cm2, open circuit voltage, V OC of 1.236 V, fill factor, FF of 85.49% and photoconversion efficiency, PCE of 25.03% with optimized SLG/Mo/Cu 2 MnSnS 4 /SnS 2 /ZnMgO/ZnO:Al/Pt structure under AM1.5G irradiation. Furthermore, a detailed comparison among recent studies has been carried out to demonstrate the significance of the proposed structure, challenges, and future prospects. Thus, obtained results pave significant resources and emancipate a new pathway to fabricate enviro-benign, cost-competitive, high-efficiency CMTS-thin film photovoltaics. [ABSTRACT FROM AUTHOR]

Organic-inorganic perovskite solar cells (PrSCs) have emerged as a promising solar photovoltaic technology in terms of realizing high power conversion efficiency (PCE). However, their limited lifetime and poor device stability limit their commercialization in future. In this regard, interface engineering of the electron transport layer (ETL) using 2D materials have been currently used owing to their high carrier mobility, high thermal stability and tunable work function which in turn enormously impact the charge carrier dynamics. In this work, we report an easy and effective way of simultaneously enhancing the efficiency and air-stability of PrSCs via interface engineering by incorporating 2D-MoS 2 (bi/tri-layered) in mesoporous-titanium dioxide (mp -TiO 2) scaffold electron transport buffer layer, and using CVD grown perovskite layers. The PrSCs were fabricated in ambient air conditions in device configuration, FTO/c-TiO 2 / mp -TiO 2 :2D-MoS 2 /CH 3 NH 3 PbI 3 /P3HT/Au, with an active area of 0.16 cm2. The best device using c -TiO 2 / mp -TiO 2 :2D-MoS 2 (0.5 wt%) ETL exhibited a substantial increase in PCE ∼13.04% as compared to PCE ∼8.75% realized in reference device fabricated without incorporating MoS 2 in mp -TiO 2 buffer layer. The incorporation of MoS 2 nanoflakes in mp -TiO 2 ETL not only enhances the PCE to ∼49%, but also improve the lifetime (retaining PCE ∼86% of its initial value up to 500 hrs, without encapsulation). The enhancement in performance of c -TiO 2 / mp -TiO 2 :2D-MoS 2 ETL based devices as compared with reference c -TiO 2 / mp -TiO 2 ETL based devices is attributed to, (i) reduction in the work function of mp -TiO 2 ETL buffer on dispersion of 2D-MoS 2 nanoflakes forming of a perfect interface at ETL/perovskite offering extremely less interfacial energy barrier to promote the charge extraction process at the interface, and suppress the surface recombination losses, (ii) fast charge collection as 2D-MoS 2 in TiO 2 strongly support the electron transport due to their highly crystalline nature, and (iii) lifetime improvement due to better moisture stability of 2D-MoS 2 and high quality of chemical vapor grown perovskite thin films. This work presents an efficient mp -TiO 2 :2D-MoS 2 scaffold ETL for realizing high performance, low cost, air-processed PrSCs for their future development. [Display omitted] • CH 3 NH 3 PbI 3 perovskite film was deposited by CVD in perovskite solar cells. • [ mp -TiO 2 :2D-MoS 2 ] buffer layer improved the performance. • Addition of 2D-MoS 2 in mp -TiO 2 suppress interface traps, promote charge extraction, and transport. • 2D-MoS 2 also improves the operational stability of the devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cr 2 O 3 @GPs/CNTs nanocomposite was fabricated to tune the electron transport layer of solar cells and X-ray detectors. • Hybrid ETLs with Cr 2 O 3 @GP and Cr 2 O 3 @CNT exhibited improved PCE of 18.5% and 26.8%. • The ETL conductivity significantly improved, and the series resistance declined. • After 336-hour stability measurement, the hybrid ETL still had almost 96% of its initial PCE. • The X-ray detector's sensitivity increased by 24.7% and 28.1%, for Cr 2 O 3 @GP and Cr 2 O 3 @CNT, respectively. Perovskites hold great promise for the fabrication of solar cells with high efficiency and low costs. Power conversion efficiencies (PCEs) have increased dramatically, highlighting the remarkable potential of perovskite materials. It has been found that charge transport layers are crucial for the functionality and durability of devices. Particularly in perovskite solar cells (PSCs), charge extraction at the interface is not particularly effective when using a conventional PCBM as an electron transport layer (ETL). Cr 2 O 3 exhibits better stability under UV exposure and better band alignment with the perovskite layer, which is beneficial for electron extraction. However, the low conductivity and mobility of Cr 2 O 3 can be improved by fabricating hybrid composites with graphitic particles (GPs) and carbon nanotubes (CNTs). Hybrid ETLs with Cr 2 O 3 @GP and Cr 2 O 3 @CNT exhibited improved PCE of 18.5% and 26.8% as compared to plane ETL. When Cr 2 O 3 @GP/CNT was added to the ETL, the ETL conductivity significantly improved, and the series resistance declined. In addition, after a 336-hour stability measurement, the hybrid ETL still had almost 96% of its initial PCE. Moreover, the X-ray detector's sensitivity increased by 24.7% and 28.1%, for Cr 2 O 3 @GP and Cr 2 O 3 @CNT, respectively. These findings provide a path for commercializing PSCs and X-ray detectors by presenting a feasible method to significantly improve their stability and performance. [ABSTRACT FROM AUTHOR]

The need for an excellent electron transport layer (ETL) material is immensely significant for higher conversion efficiency of perovskite solar cells (PSCs). This work centers on the exceptional performance achieved by the Al-doped ZnO (AZO) ETL with reference to undoped ZnO (ZnO). Both doped and undoped ETL materials were synthesized and characterized to determine their structural, morphological, and optical behavior. In this work, solar cell performance of two similar CsPbIBr 2 -based PSCs with different ETLs namely FTO/ZnO/CsPbIBr 2 /NiO (Cell #1) and FTO/AZO/CsPbIBr 2 /NiO (Cell #2) are investigated through numerical simulation method. The obtained characteristics affirms that Cell #2 offers sufficient better performance parameters (J sc , V oc , FF, and η ) against Cell #1 with respect to variation in CsPbIBr 2 PVT, ETL and HTL thickness. The adverse effect on J-V characteristics caused by controllable introduction of defect density (N t) in PVT layer is negligible for Cell #2 compared to its ZnO counterpart. Further, the contribution of AZO ETL layer on cell's performance is evaluated in terms of variation in respective ETL and HTL thickness. The investigation reveals that Cell #2 offers a desirable η of 19.46% at electron capture cross section of 2 × 10−15 cm2 while Cell #1 delivers only 12.48%. • Highly conductive Al-doped zinc oxide (AZO) layer was synthesized using a solution process. • The performance of all-inorganic perovskite solar cells was determined using simulation. • By applying an AZO electron transport layer, over 19 % efficiency was achieved for perovskite solar cells. [ABSTRACT FROM AUTHOR]

Most previous studies of perovskite core/shell structures have been based on ZnO/TiO2 nanowires (NWs), which are not suitable for high photoelectric conversion efficiency. Here, core/shell ZnO/TiO2 NWs with AgCl-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We designed CdSe with AgCl dopants that were synthesized by a colloidal process. An improvement of the recombination barrier (Rct1), due to shell supplementation with AgCl-doped CdSe quantum dots, improved the open circuit voltage, the fill factor, and the adsorption capacity of CH3NH3PbI3 perovskite with NWs. The enhanced cell steady state was attributable to TiO2 with AgCl-doped CdSe QD supplementation. A maximum power conversion efficiency of 15.12% was attained in an atmospheric environment. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 core/shell arrays was investigated to represent the merit of ZnO/TiO2 core/shell arrays as an electron transport layer in effective devices. These results showed an uncomplicated approach for restraining non-radiative recombination loss in hetero-structure core/shell arrays to significantly improve perovskite solar cell performance and increase the effectiveness of photovoltaics.

In this study, spatial atomic layer deposition (sALD) is employed to prepare titanium dioxide (TiO2) thin films by using titanium tetraisopropoxide and water as metal and water precursors, respectively. The post-annealing temperature is varied to investigate its effect on the properties of the TiO2 films. The experimental results show that the sALD TiO2 has a similar deposition rate per cycle to other ALD processes using oxygen plasma or ozone oxidant, implying that the growth is limited by titanium tetraisopropoxide steric hindrance. The structure of the as-deposited sALD TiO2 films is amorphous and changes to polycrystalline anatase at the annealing temperature of 450 °C. All the sALD TiO2 films have a low absorption coefficient at the level of 10−3 cm−1 at wavelengths greater than 500 nm. The annealing temperatures of 550 °C are expected to have a high compactness, evaluated by the refractive index and x-ray photoelectron spectrometer measurements. Finally, the 550 °C-annealed sALD TiO2 film with a thickness of ~8 nm is applied to perovskite solar cells as a compact electron transport layer. The significantly enhanced open-circuit voltage and conversion efficiency demonstrate the great potential of the sALD TiO2 compact layer in perovskite solar cell applications.

In halide perovskite solar cells (PSCs), moderate lead iodide (PbI 2 ) can enhance device efficiency by providing some passivation effects, but extremely active PbI 2 leads to the current density-voltage hysteresis effect and device instability. In addition, defects distributed on the buried interface of tin oxide (SnO 2 )/perovskite will lead to the photogenerated carrier recombination. Here, rubidium chloride (RbCl) is introduced at the buried SnO 2 /perovskite interface, which not only acts as an interfacial passivator to interact with the uncoordinated tin ions (Sn 4+ ) and fill the oxygen vacancy on the SnO 2 surface but also converts PbI 2 into an inactive (PbI 2 ) 2 RbCl compound to stabilize the perovskite phase via a bottom-up evolution effect. These synergistic effects deliver a champion PCE of 22.13% with suppressed hysteresis for the W RbCl PSCs, in combination with enhanced environmental and thermal stability. This work demonstrates that the interfacial defect passivation and bottom-up excess PbI 2 management using RbCl modifiers are promising strategies to address the outstanding challenges associated with PSCs.

Perovskite solar cells show great potential application prospects in the field of solar cells due to their promising properties. However, most perovskite solar cells that exhibit excellent photovoltaic performance typically require a carrier transport layer that necessitates a high-temperature annealing process. This greatly restricts the scalability and compatibility of perovskite solar cells in flexible electronics. In this paper, SnO 2 nanoparticles with high crystallinity, good dispersibility and uniform particle size distribution are first prepared using a solvothermal method and dispersed in n-butanol solution. SnO 2 electron transport layers are then prepared by a low-temperature spin coating method, and the photovoltaic characteristics of perovskite solar cells prepared with different SnO 2 nanoparticles/n-butanol concentrations are studied. Results indicate that the rigid perovskite solar cell achieves the highest power conversion efficiency of 15.61% when the concentration of SnO 2 nanoparticles/n-butanol is 15 mg mL -1 . Finally, our strategy is successfully applying on flexible perovskite solar cells with a highest PCE of 14.75%. Our paper offers a new possibility for large-scale preparation and application of perovskite solar cells in flexible electronics in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Xie and Que.)

Recent studies have focused on exploring the potential of resistive random-access memory (ReRAM) utilizing halide perovskites as novel data storage devices. This interest stems from its notable attributes, including a high ON/OFF ratio, low operating voltages, and exceptional mechanical properties. Nevertheless, there have been reports indicating that memory systems utilizing halide perovskites encounter certain obstacles pertaining to their stability and dependability, mostly assessed through endurance and retention time. Moreover, the presence of these problems can potentially restrict their practical applicability. This study explores a resistive switching memory device utilizing MAPbBr 3 perovskite, which demonstrates bipolar switching characteristics. The device fabrication procedure involves a low-temperature, all-solution process. For the purpose of enhancing the device's reliability, the utilization of TPBI(2,2',2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) as an electron transfer material on the MAPbBr 3 switching layer was implemented for the first time. The formation and rupture of Ag filaments in the MAPbBr 3 perovskite switching layer are attributed to reduction-oxidation reactions. The TPBI is involved in the regulation of filaments during the SET and RESET processes. Hence, it can be shown that the MAPbBr 3 device incorporating TPBI exhibited about 1000 endurance cycles when subjected to continuous voltage pulses. Moreover, the device consistently maintained ON/OFF ratios above 10 7 . In contrast, the original MAPbBr 3 device without TPBI demonstrated a significantly lower endurance with only 90 cycles observed. In addition, the MAPbBr 3 device integrated with TPBI exhibited a retention time exceeding 3 × 10 3 s. The findings of this research provide compelling evidence to support the notion that electron transfer materials have promise for the development of halide perovskite memory systems owing to their favorable attributes of dependability and stability.

Antimony selenide (Sb 2 Se 3 ) is a highly promising photovoltaic material thanks to its outstanding optoelectronic properties, as well as its cost-effective and eco-friendly merits. However, toxic CdS is widely used as an electron transport layer (ETL) in efficient Sb 2 Se 3 solar cells, which largely limit their development toward market commercialization. Herein, an effective green Cd-free ETL of SnO x is introduced and deposited by atomic layer deposition method. Additionally, an important post-annealing treatment is designed to further optimize the functional layers and the heterojunction interface properties. Such engineering strategy can optimize SnO x ETL with higher nano-crystallinity, higher carrier density, and less defect groups, modify Sb 2 Se 3 /SnO x heterojunction with better interface performance and much desirable "spike-like" band alignment, and also improve the Sb 2 Se 3 light absorber layer quality with passivated bulk defects and prolonged carrier lifetime, and therefore to enhance carrier separation and transport while suppressing non-radiative recombination. Finally, the as-fabricated Cd-free Mo/Sb 2 Se 3 /SnO x /ITO/Ag thin-film solar cell exhibits a stimulating efficiency of 7.39%, contributing a record value for Cd-free substrate structured Sb 2 Se 3 solar cells reported to date. This work provides a viable strategy for developing and broadening practical applications of environmental-friendly Sb 2 Se 3 photovoltaic devices., (© 2023 Wiley-VCH GmbH.)

The presence of TiO 2 used as an efficient electron transport layer is crucial to achieving high-performance solar cells, especially for a hole transport material (HTM)-free carbon-based perovskite solar cell (PSC). The hydrolysis of TiCl 4 is one of the most widely used routes for forming TiO 2 layer in solar cells, which includes the stock solution preparation from TiCl 4 initial precursor and the thermal hydrolysis of the stock solution. The second thermal hydrolysis step has been extensively studied, while the initial hydrolysis reaction in the first step is not receiving sufficient attention, especially for its influence on the photovoltaic performance of HTM-free carbon-based devices. In this study, the role of TiCl 4 stock solution in the growth process of TiO 2 layer is examined. Based on the analysis of the Ti(IV) intermediate states for different TiCl 4 concentrations from Raman spectra, 2 M TiCl 4 precursor exhibits moderate nucleation and growth kinetics without generating too many intermediates which occurs in 3 M TiCl 4 precursor, yielding ∼300 nm size spherical TiO 2 agglomerates with a rutile phase. In the aspect of devices, the HTM-free carbon-based PSCs fabricated using 2 M TiCl 4 precursor deliver a conversion efficiency beyond 17%, which may be attributed to the reduced defect in compact TiO 2 layer., (© 2023 IOP Publishing Ltd.)