Recent Development of Transparent Conducting Oxide‐Free Flexible Thin‐Film Solar Cells

Guo, Wenxi; Zhang, Xu; Zhang, Fayin; Xie, Shuyao; Xu, Hongyao; Liu, Xiang Yang

doi:10.1002/adfm.201603378

Cited by 89 publications

(60 citation statements)

References 233 publications

(195 reference statements)

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“…Ag NW electrodes have been attracting a great deal of concerns due to their having high flexibility, transparency, electrical conductivity, and low cost among the various alternative flexible electrodes 11–15 . While almost all candidates for alternative transparent electrodes show excellent flexibility in comparison with the most widely used indium-tin-oxide (ITO) electrodes, their sheet resistances, transmittances, and production costs still do not match those of ITO films 16, 17 . Some mobile phones that use rigid plastic substrates have already been released, and electronic devices based on flexible substrates are expected to be commercialized in the near future 18 .…”

Section: Introductionmentioning

confidence: 99%

Degradation mechanisms of silver nanowire electrodes under ultraviolet irradiation and heat treatment

Choo

Kim

2017

Sci Rep

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We report the degradation mechanisms of the silver nanowire (Ag NW) electrodes that play a significantly important role in the stability of wearable and flexible devices. The degradation mechanisms behind the increase in the sheet resistances of Ag NW electrodes were clarified by investigating the variations in the structure and the chemical composition of the Ag NW electrodes caused by ultraviolet irradiation and thermal treatment. While the shapes of the Ag NWs were affected by melting during the thermal degradation process, the chemical composition of the polyvinylpyrrolidone protective layer on the surfaces of the Ag NWs was not changed. Ultraviolet irradiation deformed the shapes of the Ag NWs because nitrogen or oxygen atoms were introduced to the silver atoms on the surfaces of the Ag NWs. A graphene-oxide flake was coated on the Ag NW electrodes by using a simple dipping method to prevent ultraviolet irradiation and ozone contact with the surfaces of the Ag NWs, and the increase in the sheet resistance in the graphene-oxide-treated Ag NWs was suppressed. These observations will be of assistance to researchers trying to find novel ways to improve the stability of the Ag NW electrodes in next-generation wearable devices.

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Section: Introductionmentioning

confidence: 99%

Degradation mechanisms of silver nanowire electrodes under ultraviolet irradiation and heat treatment

Choo

Kim

2017

Sci Rep

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“…It is clear that the PET/ITO electrode shows an increase of more than 1000 times in R / R O after only 100 bending cycles. This quick failure in electrical conduction is attributed to the brittle nature of ITO . However, there is only a little R / R O variation for AgNWs‐based FTEs even after 2000 bending cycles, indicating their high mechanical robustness.…”

Section: Resultsmentioning

confidence: 99%

“…Undoubtedly, ITO or FTO is the most commonly used transparent conductor due to its excellent electrical conductivity (with a sheet resistance of 10–20 Ω sq −1 ) and optical transparency (with a transmittance of 85–90% over the visible wavelength region) . However, its role in flexible optoelectronic devices is limited due to the inherent shortcomings of brittleness, material scarcity, as well as high‐temperature and low‐throughput deposition process . To date, several FTEs such as graphene, metal grids, and silver nanowires (AgNWs) have been exploited to replace ITO and FTO, since they show extraordinary electrical, optical, and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Flexible Perovskite Solar Cells Enabled by Low‐Temperature ALD‐Assisted Surface Passivation

Jin

et al. 2018

Advanced Optical Materials

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In addition to the extremely high efficiency, mechanical flexibility and solution processability of perovskite materials offer the great potential towards large-scale roll-to-roll manufacturing of PeSCs. [9][10][11][12][13] To achieve high-performance flexible PeSCs, three key issues must be addressed: 1) new flexible transparent electrode (FTE) solutions to replace the brittle indium-tin-oxide (ITO) or fluorine-doped tin-oxide (FTO) electrode, 2) low-temperature processing of all functional layers to match the thermal limit of plastic substrates, and 3) interface engineering to minimize the charge recombination loss.Undoubtedly, ITO or FTO is the most commonly used transparent conductor due to its excellent electrical conductivity (with a sheet resistance of 10-20 Ω sq −1 ) and optical transparency (with a transmittance of 85-90% over the visible wavelength region). [14] However, its role in flexible optoelectronic devices is limited due to the inherent shortcomings of brittleness, material scarcity, as well as high-temperature and low-throughput deposition process. [15,16] To date, several FTEs such as graphene, [17] metal grids, [18] and silver nanowires (AgNWs) [19] have been exploited to replace ITO and FTO, since they show extraordinary electrical, optical, and mechanical properties. Especially, AgNWs-based random network is solution processable and cost effective, making it one of the most promising candidates for alternative FTEs in flexible PeSCs. [20][21][22] Regardless of a strong potential to replace ITO, several obstacles should be overcome for AgNWs-based FTEs. First, the randomly distributed AgNWs during the solution process result in high surface roughness, which may cause the electrical short-circuits in the overlapped perovskite films due to the protuberant nodes of AgNWs. [20,21] Second, AgNWs suffer from the chemical reaction when they are in direct contact with halide perovskite films, which would severely restrict the device performance. [22,23] Third, the electrical failure and instability of AgNWs may occur due to Joule heating at the junctions of nanowires. [24,25] To solve the aforementioned issues, a feasible solution is to insert a buffer layer between AgNWs and perovskite films to reduce surface roughness and improve the electrical stability of AgNWs-based FTEs. The buffer layer should be sufficiently transparent and conductive without sacrificing the optical Flexible perovskite solar cells (PeSCs) hold great potential as a leading technology for large-scale roll-to-roll production of highly efficient renewable energy sources. To achieve long-term bendability and competitive photovoltaic properties for flexible PeSCs, an efficient strategy is reported for a fully indium-free flexible composite electrode, consisting of solution-processed silver nanowires (AgNWs) conductive network, a sol-gel-derived ZnO protective layer for smoothing the surface, and an atomic-layer-deposited TiO 2 passivation layer for eliminating the perovskite decomposition. The synergetic interplay of this electrod...

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“…In previous reviews, the transparent electrodes and cell configuration of PSCs have been covered, but specific issues related to the integration of PSCs and MeNW-network electrodes have not been discussed in detail. [30][31][32] In this review, we have made an effort to have tighter focus on MeNW-electrode-integrated PSCs and have also attempted to highlight the critical issues associated with integrating MeNW-network electrodes and provide characteristic experimental designs to resolve them. A brief introduction of PSCs and MeNW-network electrodes is given in Section 2, and the advantageous features, in terms of cell fabrication and functionalities, observable in MeNW-integrated PSCs are described in Section 3.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Nanowire‐Electrode‐Based Perovskite Solar Cells: Challenging Issues and New Opportunities

Ahn

Hwang

Jeong

et al. 2017

Advanced Energy Materials

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in PSCs has been accomplished within a relatively short period of time, owing to OMHP's merits for low-cost, large-area, flexible photovoltaic applications; these merits include (i) the precursor chemicals, including organic ammonium halides and lead (tin) halides, for synthesizing the OMHP materials are cost-effective, and the OMHP layers can be readily prepared by simple wet-chemical approaches such as a spin coating or a slot-die coating process; (ii) the processing temperatures are relatively low, below 150 °C, for the formation of well-crystalized OMHP layers, in contrast to other thin-film-based solar cells; (iii) both the high absorption coefficients [6] and high carrier mobilities [7] suggest promising possibilities for highperformance photoactive materials. The PCE certified by National Renewable Energy Laboratory (NREL) reached 22.1% in 2016, [8] which is either comparable to or outperforms the PCEs of other next-generation thin-film solar cells, including CIGS(Se) (22.3%), CZTS/Se (12.6%), CdTe (22.1%), and organic photovoltaics (OPVs, 11.5%).Apart from the race to achieve higher PCE, other important research has been directed toward the development of lead-free OMHP layers, [9] large-area device fabrication, [10,11] a methodology of achieving long-term stability against moisture and irradiation, [12,13] and a way of recycling constituent cell materials. [14] Another fascinating research topic concerns the electrodes for PSCs. To date, vacuum-deposited transparent conductive oxides (TCOs), such as indium tin oxide (ITO) and fluorinated tin oxide (FTO), have been used widely as a large-area window electrode through which light passes. However, TCOs have received criticism in terms of their fabrication cost, brittleness, and the scarcity of raw materials (especially, the indium in ITO). [15] Opaque noble metal electrodes (Au, Ag), which are usually used as a back contact, are also fabricated with a costly vacuum-assisted deposition process. From the viewpoint of cost-effectiveness, both transparent and opaque conventional electrodes apparently represent predominant impediments to the high-throughput fabrication of PSCs, giving rise to a significant demand to replace these conventional electrodes with alternatives.To date, a variety of alternative electrodes have been reported in the literature.

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Recent Development of Transparent Conducting Oxide‐Free Flexible Thin‐Film Solar Cells

Cited by 89 publications

References 233 publications

Degradation mechanisms of silver nanowire electrodes under ultraviolet irradiation and heat treatment

Degradation mechanisms of silver nanowire electrodes under ultraviolet irradiation and heat treatment

High‐Performance Flexible Perovskite Solar Cells Enabled by Low‐Temperature ALD‐Assisted Surface Passivation

Metal‐Nanowire‐Electrode‐Based Perovskite Solar Cells: Challenging Issues and New Opportunities

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