Junctionless thin-film ferroelectric oxides for photovoltaic energy production

In the last decade, photovoltaics (PV) has experienced an important transformation. Traditional solar cells formed by compact semiconductor layers have been joined by new kinds of cells that are constituted by a complex mixture of organic, inorganic and solid or liquid electrolyte materials, and rely on charge separation at the nanoscale. Recently, metal organic halide perovskites have appeared in the photovoltaic landscape showing large conversion efficiencies, and they may share characteristics of the two former types. In this paper we provide a general description of the photovoltaic mechanisms of the single absorber solar cell types, combining all-inorganic and hybrid and organic cells into a single framework. The operation of the solar cell relies on a number of internal processes that exploit internal charge separation and overall charge collection minimizing recombination. There are two main effects to achieve the required efficiency, first to exploit kinetics at interfaces, favouring the required forward process, and second to take advantage of internal electrical fields caused by a built-in voltage and by the distribution of photogenerated charges. These principles represented by selective contacts, interfaces and the main energy diagram, form a solid base for the discussion of the operation of future types of solar cells. Additional effects based on ferroelectric polarization and ionic drift provide interesting prospects for investigating new PV effects mainly in the perovskite materials.

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“…These materials have suitable optical and electronic properties for a PV absorber material. [45][46][47] One route for …”

Section: Ferroelectric Photovoltaic Effectsmentioning

confidence: 99%

Classification of solar cells according to mechanisms of charge separation and charge collection

Kirchartz

Bisquert

Mora‐Seró

et al. 2015

Phys. Chem. Chem. Phys.

106

108

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“…The microstructural, electrical, and optical properties of FTO are sensitive to deposition technique and conditions [6,7]. Streaming Process for Electrodeless Electrochemical Deposition (SPEED) [8][9][10][11], which was developed by SISOM Thin Films LLC, is a high-rate uniform deposition technique that uses water-soluble precursors to rapidly coat the substrate with nanoparticle-based films. SPEED has its foundation in chemical bath deposition (CBD) [8][9][10] and is distinct from spray pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Optical and electrical properties of tin oxide-based thin films prepared by streaming process for electrodeless electrochemical deposition

Khalilzadeh-Rezaie

Oladeji²,

Yusuf

et al. 2015

MRS Proc.

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Transparent conducting thin-films of SnO2: F were grown on preheated glass, Al2O3 coated glass, and quartz substrates by Streaming Process for Electrodeless Electrochemical Deposition (SPEED). Stannic chloride (SnCl4) and ammonium fluoride (NH4F) dissolved in a mixture of deionized water and organic solvents were used as precursors. The preheated substrate temperature was varied between 440 and 500 °C. High quality SnO2:F films were grown at all the substrate temperatures studied. The resulting typical film thickness was 250 nm. X-ray diffraction shows that the grown films are polycrystalline SnO2 with a tetragonal crystal structure. The average optical transmission of the films was around 93% throughout the wavelength range 400 to 1000 nm. The lowest electrical resistivity achieved was 6 × 10-4 Ω-cm. The Hall measurements showed that the film is an n-type semiconductor, with carrier mobility of 8.3 cm2/V-s, and carrier concentration of 1 × 1021 cm-3. The direct bandgap was determined to be 4.0 eV from the transmittance spectrum.

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“…Figure 6 shows an illustration of a KBNN supercell, in which an oxygen vacancy (denominated as N i − V o − N b) has been included [54]. The remanent polarization value for the KBNNO system have been reported between 0.1 -0.3 C/m 2 [10, 45,51,55]. When compared to other ferroelectrics, these polarization values reported for KBNNO are considered relatively low due to be limited by ferroelectric in sintered pellets.…”

Section: Kbnn Systemmentioning

confidence: 99%

“…When compared to other ferroelectrics, these polarization values reported for KBNNO are considered relatively low due to be limited by ferroelectric in sintered pellets. In spite of these values be low, it allows open-circuit voltages (V oc ) higher than the bandgap values observed of these materials, which is important to photocarrier separation and photo-current across the bulk [10,55]. Thus, the photovoltaic eect in ferroelectrics occurs in a dierent way to the conventional semiconductors pn junction [54,55].…”

Section: Kbnn Systemmentioning

confidence: 99%

“…In spite of these values be low, it allows open-circuit voltages (V oc ) higher than the bandgap values observed of these materials, which is important to photocarrier separation and photo-current across the bulk [10,55]. Thus, the photovoltaic eect in ferroelectrics occurs in a dierent way to the conventional semiconductors pn junction [54,55]. Therefore, this type of ferroelectric perovskite could show a strong piezoelectric and/or pyroelectric response together with a considerable photovoltaic eect.…”

Section: Kbnn Systemmentioning

confidence: 99%

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Synthesis and physical characterization of KNbO3-based electro-ceramics

Silva¹

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Os materiais ferroelétricos baseados em KN bO 3 têm sido amplamente investigados como resultado de muitas propriedades físicas interessantes que os tornam adequados para o desenvolvimento de componentes eletrônicos multifuncionais. Em particular, soluções sólidas ferroelétricas detêm recebido especial atenção para aplicações ópticas, inclusive para dispositivos fotovoltaicos de alto desempenho. Neste trabalho, cerâmicas de KBNN foram produzidas por meio do método de sinterização convencional (reação de estado sólido), e as propriedade estruturais, microestruturais, elétricas e ópticas foram investigadas. Os resultados foram analisados e discutidos considerando o efeito dos defeitos estruturais de vacâncias de oxigênio nesses materiais e do tamanho do grão, no caso especíco da resposta elétrica observada. Os resultados obtidos sugerem que os materiais propostos, baseados em óxidos ferroelétricos semicondutores com estrutura perovskita, são uma boa alternativa para aplicações em células solares.Palavras-chave : cerâmicas, KN bO 3 , vacâncias, ferroelétricos, dispositivos fotovoltaicos.

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Junctionless thin-film ferroelectric oxides for photovoltaic energy production

Cited by 3 publications

References 13 publications

Classification of solar cells according to mechanisms of charge separation and charge collection

Classification of solar cells according to mechanisms of charge separation and charge collection

Optical and electrical properties of tin oxide-based thin films prepared by streaming process for electrodeless electrochemical deposition

Synthesis and physical characterization of KNbO3-based electro-ceramics

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