Anode Interfacial Tuning via Electron‐Blocking/Hole‐Transport Layers and Indium Tin Oxide Surface Treatment in Bulk‐Heterojunction Organic Photovoltaic Cells

Hains, Alexander W.; Li, Jun; Martinson, Alex B. F.; Irwin, Michael D.; Marks, Tobin J.

doi:10.1002/adfm.200901045

Cited by 179 publications

(185 citation statements)

References 128 publications

(184 reference statements)

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“…It is possibly through the reduction of the concentration of oxygen ARTICLE vacancy and therefore a downshift of Fermi level 31 . It has already been confirmed that UVO treatment has an effect on electrical and photovoltaic properties of metal oxides 28,29 . A reduced electron concentration of the FTO surface layer is expected to lower interfacial recombination and improve V OC .…”

Section: Resultsmentioning

confidence: 82%

“…The improved coverage should reduce the amount of direct contact between the FTO and the HTL, which should result in increased R sh and carrier lifetime, and therefore V OC . Furthermore, UVO treatment has also been widely reported to increase the work functions of metal oxides [28][29][30][31] . It is possibly through the reduction of the concentration of oxygen ARTICLE vacancy and therefore a downshift of Fermi level 31 .…”

Section: Resultsmentioning

confidence: 99%

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Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

et al. 2015

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Efficient lead halide perovskite solar cells use hole-blocking layers to help collection of photogenerated electrons and to achieve high open-circuit voltages. Here, we report the realization of efficient perovskite solar cells grown directly on fluorine-doped tin oxide-coated substrates without using any hole-blocking layers. With ultraviolet-ozone treatment of the substrates, a planar Au/hole-transporting material/CH 3 NH 3 PbI 3-x Cl x /substrate cell processed by a solution method has achieved a power conversion efficiency of over 14% and an open-circuit voltage of 1.06 V measured under reverse voltage scan. The open-circuit voltage is as high as that of our best reference cell with a TiO 2 hole-blocking layer. Besides ultraviolet-ozone treatment, we find that involving Cl in the synthesis is another key for realizing high open-circuit voltage perovskite solar cells without hole-blocking layers. Our results suggest that TiO 2 may not be the ultimate interfacial material for achieving high-performance perovskite solar cells.

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Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

et al. 2015

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“…Moreover, for larger positive voltage, the conductivity is much higher than other two diodes, and ohmic transport is observed for the applied voltage of more than 4 V, which demonstrates the validity of modifying anode to extraction of holes in organic diodes by using a buffer layer of high work function. [26,27] In conclusion, we realized the tuning of band-bending of pentacene by using the substrate of different work function, downward bending with a low work function, flat band with a middle work function, and upward bending with a high work function. The formation of band-bending was explained by the electrostatic potential according to the position of Fermi level.…”

Section: Wwwadvelectronicmatdementioning

confidence: 99%

Relation between Interfacial Band‐Bending and Electronic Properties in Organic Semiconductor Pentacene

Zhang

Zhao

Wang

et al. 2017

Adv Elect Materials

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carriers transport across the organic/electrode interface, such as charge injection in organic thin-film transistors and organic light-emission diodes, and carrier extraction in organic photovoltaic cells. Metal oxides were used as buffer layer under the anodes to increase their work function (WF), and enhance hole transport across the organic/electrode interface. [11][12][13][14][15][16][17] The energy level alignment has been extensively argued in many reports; [18][19][20][21][22] several models have been proposed to understand their interfacial electronic structures. The electrostatic model based on the density of states in the organic semiconductor predicted the band-bending in organic semiconductors for different work functions. [23,24] So far, most of the organic electronic devices still depend on the intrinsic properties of organic materials, and the interfacial electronic structures have not been vastly employed to realize the function of semiconductor devices. Therefore, it still remains a challenge for the effective tailoring of interfacial electronic structures to achieve the desired electronic properties in real electronic devices. Here, we demonstrated that the band-bending in organic semiconductors can be tuned by using the substrates with different work functions, and different interfacial structures leaded to various electronic transport properties. The works are promising exploration to realize the function of semiconductor devices by tailoring the desired interfacial electronic structures.We selected typical organic semiconductor pentacene to investigate the interfacial band-bending, and substrates were selected from high work function to low work function, i.e., PEDOT:PSS/ITO (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate/indium tin oxide) of 5.4 eV work function, ITO of 4.1 eV, and PbO/ITO of 3.5 eV. The pentacene/ITO interface was first studied by using the in situ ultraviolet photoelectron spectroscopy (UPS), which is very effective and a direct tool to investigate interfacial electronic structures. Figure 1a gives the molecular structures of pentacene, and Figure 1b shows the UPS spectra of different pentacene coverage on ITO substrate, left panel is the secondary electron cut-off, which represents the work function of the film, and right panel is the valenceband photoelectron spectra in which the onset of first peak represents the highest occupied molecular orbital (HOMO). The work function of ITO is determined as 4.1 eV, which is about 0.9 eV above the HOMO of pentacene. From UPS and inverse photoelectron spectroscopy, [25]

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“…In addition to aforementioned IFL materials types, some other classes of materials have also been developed and incorporated into PSCs, mainly including self-assembly monolayers (SAMs) [121][122][123][124], crosslinked semiconducting blends [125,126], multifunctional quantum-dot monolayers [127], and inorganic salts [128]. As emerging IFLs for polymer solar cells, these materials have shown some promising characteristics for performance enhancement and stability improvement.…”

Section: Other Interfacial Layer Materialsmentioning

confidence: 99%

Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells

et al. 2015

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Improving power conversion efficiency and device performance stability is the most critical challenge in polymer solar cells for fulfilling their applications in industry at large scale. Various methodologies have been developed for realizing this goal, among them interfacial layer engineering has shown great success, which can optimize the electrical contacts between active layers and electrodes and lead to enhanced charge transport and collection. Interfacial layers also show profound impacts on light absorption and optical distribution of solar irradiation in the active layer and film morphology of the subsequently deposited active layer due to the accompanied surface energy change. Interfacial layer engineering enables the use of high work function metal electrodes without sacrificing device performance, which in combination with the favored kinetic barriers against water and oxygen penetration leads to polymer solar cells with enhanced performance stability. This review provides an overview of the recent progress of different types of interfacial layer materials, including polymers, small molecules, graphene oxides, fullerene derivatives, and metal oxides. Device performance enhancement of the resulting solar cells will be elucidated and the function and operation mechanism of the interfacial layers will be discussed. OPEN ACCESSPolymers 2015, 7 334

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Anode Interfacial Tuning via Electron‐Blocking/Hole‐Transport Layers and Indium Tin Oxide Surface Treatment in Bulk‐Heterojunction Organic Photovoltaic Cells

Cited by 179 publications

References 128 publications

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Relation between Interfacial Band‐Bending and Electronic Properties in Organic Semiconductor Pentacene

Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells

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