Influence of annealing treatments on solution-processed ZnO film deposited on ITO substrate as electron transport layer for inverted polymer solar cells

Morvillo, P.; Diana, Rosita; Mucci, Adele; Bobeico, E.; Ricciardi, Rosa; Minarini, Carla

doi:10.1016/j.solmat.2015.05.038

Cited by 34 publications

(22 citation statements)

References 39 publications

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“…Indeed, promoting the release of insulating acetate groups from the forming ZnO lm is expected to enhance the electron extraction ability of the ETL by limiting detrimental phenomena such as recombination or trapping of charge carriers. 23,33 Furthermore, the lower leakage current extrapolated from the J-V characteristics in the dark (see Fig. S4 in ESI †) corroborated these considerations, thus conrming the better charge selectivity of PSCs incorporating ZnO-r4 compared to ZnO-r2 and ZnO-r6.…”

Section: Because the [H 2 O]/[zn 2+supporting

confidence: 59%

“…32 Despite the key role played by these two interplaying processes in the production of the nal ZnO thin solid lm, their inuence on the functional properties of the resulting PSCs has been surprisingly overlooked. 33 In particular, no examples of systematic approaches to control and ultimately promote the hydrolysis and condensation steps during the formation of ZnO ETLs via sol-gel process have been presented in the literature to date, notwithstanding their potential to further improve PSC device efficiency.…”

Section: Introductionmentioning

confidence: 99%

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The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

et al. 2016

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A new approach is proposed in this work to chemically control the low-temperature sol-gel formation of ZnO thin films used as efficient electron transporting layers (ETLs) in inverted polymer solar cells (PSCs). The chemical composition of the ZnO sol-gel precursor was modified by systematically employing different [H2O]/[Zn2+] molar ratios in the starting sol formulation and evaluating their influence on film properties and PSC device performance. A thorough characterization of the obtained ZnO ETLs evidenced the key importance of the [H2O]/[Zn2+] molar ratio to achieve effective control on the sol-gel hydrolysis and condensation processes. Based on these evidences, a mechanism for the formation of the ZnO films at the low processing temperatures used in this work was proposed. PSC devices were fabricated incorporating ZnO ETLs obtained from ZnO sol precursor formulations with increasing [H2O]/[Zn2+] ratios and their photovoltaic characterization revealed the presence of a maximum device efficiency for intermediate [H2O]/[Zn2+] values. Finally, the effect of water in the ZnO sol precursor on the long-term (>1000 h) shelf-life of PSCs fabricated onto flexible PET substrates was investigated and a correlation was found between chemical composition of the ZnO sol precursor and device shelf-life. The results of this study give a clear demonstration of a viable strategy to achieve improved PSC device performance by chemically controlling the formation of the sol-gel based ZnO ETL at processing temperatures compatible with flexible plastic substrates and provide useful guidelines for the development of efficient sol-gel derived metal-oxide buffer layers for highly performing flexible photovoltaics

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Section: Because the [H 2 O]/[zn 2+supporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

et al. 2016

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“…1c, because the conduction band minimum (CBM) of ZnO is close to the energy of the lowest unoccupied molecular orbital (LUMO) of PCBM, electrons can be efficiently transported to the ITO cathode without significant loss. Generally, well-matched energy levels and a favorable contact interface contribute to excellent charge transport properties and overall performance of OSCs [17,18]. In fact, the energy levels and interface between the CBL and the active layer depend on the crystal structure and morphology, respectively.…”

Section: Resultsmentioning

confidence: 99%

Low-temperature preparation of ZnO thin film by atmospheric mist chemistry vapor deposition for flexible organic solar cells

Cheng

Wang

Zhang

et al. 2016

J Mater Sci: Mater Electron

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A low-temperature method for the large-scale growth of ZnO thin films on flexible substrates was realized using a mist chemistry vapor deposition setup. We prepared and analyzed ZnO thin films grown on flexible PET/ITO in the temperatures range of 125-250°C. The growth of ZnO crystallites was qualitatively investigated with respect to nucleation and substrate temperature. We observed a mixed phase in the ZnO thin films prepared at 125 and 150°C. We conclude that the optimal substrate temperature for optimal ZnO thin films growth is between 150-200°C. Our results show that the photovoltaic performance of an organic solar cell (OSC) is strongly dependent on both composition and morphology. To demonstrate its application on flexible organic optoelectronic devices, a large OSC with as-grown ZnO thin film as cathode buffer layer was successfully prepared.

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“…For instance, according to Park et al, a ZrO x dielectric was synthesized by adding hydrogen peroxide, and the fabricated dielectric film was tested as a TFT, which demonstrated a low leakage current with high breakdown strength (3.4 MV/cm) after film treatment at 350 • C [12]. Lee et al [13] fabricated a solution-processed ZrO x TFT on a glass substrate; however, the desired carrier mobility (~25 cm 2 /Vs) was achieved at a high annealing temperature of 500 • C. Ha and co-workers [14] employed solution-processed ZrO x as a gate dielectric layer of Zinc Tin Oxide (ZTO)-TFTs, which demonstrated a low operating voltage (<5 V) and high channel carrier concentration, but the optimized annealing temperature of the ZrO x dielectric film was as high as 500 • C. Oja et.al [16], Juma et al [17], and Oluwabi et al [18,19] have deposited metal oxide films by spray pyrolysis; in light of their results, the desired morphology and electrical properties were attained after annealing at temperatures above 700 • C. Also, Morvillo et.al [20] reported that annealing does not only influence the performance of metal oxide films but also influences electronic changes in their underlying substrate (e.g. ITO), which eventually makes the optimization process very challenging.…”

Section: Introductionmentioning

confidence: 99%

Influence of Post-UV/Ozone Treatment of Ultrasonic-Sprayed Zirconium Oxide Dielectric Films for a Low-Temperature Oxide Thin Film Transistor

et al. 2019

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Solution-processed metal oxides require a great deal of thermal budget in order to achieve the desired film properties. Here, we show that the deposition temperature of sprayed zirconium oxide (ZrOx) thin film can be lowered by exposing the film surface to an ultraviolet (UV) ozone treatment at room temperature. Atomic force microscopy reveals a smooth and uniform film with the root mean square roughness reduced from ~ 0.63 nm (UVO-O) to ~ 0.28 nm (UVO-120) in the UV–ozone treated ZrOx films. X-ray photoelectron spectroscopy analysis indicates the formation of a Zr–O network on the surface film, and oxygen vacancy is reduced in the ZrOx lattice by increasing the UV–ozone treatment time. The leakage current density in Al/ZrOx/p-Si structure was reduced by three orders of magnitude by increasing the UV-ozone exposure time, while the capacitance was in the range 290–266 nF/cm2, corresponding to a relative permittivity (k) in the range 5.8–6.6 at 1 kHz. An indium gallium zinc oxide (IGZO)-based thin film transistor, employing a UV-treated ZrOx gate dielectric deposited at 200 °C, exhibits negligible hysteresis, an Ion/Ioff ratio of 104, a saturation mobility of 8.4 cm2 V−1S−1, a subthreshold slope of 0.21 V.dec−1, and a Von of 0.02 V. These results demonstrate the potentiality of low-temperature sprayed amorphous ZrOx to be applied as a dielectric in flexible and low-power-consumption oxide electronics.

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Influence of annealing treatments on solution-processed ZnO film deposited on ITO substrate as electron transport layer for inverted polymer solar cells

Cited by 34 publications

References 39 publications

The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

Low-temperature preparation of ZnO thin film by atmospheric mist chemistry vapor deposition for flexible organic solar cells

Influence of Post-UV/Ozone Treatment of Ultrasonic-Sprayed Zirconium Oxide Dielectric Films for a Low-Temperature Oxide Thin Film Transistor

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