Effects of additive-solvents on the mobility and recombination of a solar cell based on PTB7-Th:PC71BM

Araújo, Francineide Lopes de; Amorim, Daniel Roger Bezerra; Torres, Bruno Bassi Millan; Coutinho, Douglas José; Faria, R.M.

doi:10.1016/j.solener.2018.11.027

Cited by 19 publications

(14 citation statements)

References 56 publications

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“…Apparently, the LNO interface layer with appropriate valence-band maximum (4.95 eV) and energy band gap (3.45 eV) matches with the energy level in conventional PTB7-Th:PC 71 BM solar cells well (Figure S1), enhancing the hole selection and transport ability. 46 Moreover, compared with classical PEDOT:PSS HTL, the LNO layer has a higher highest occupied molecular orbital level and lowest unoccupied molecular orbital level, indicating that LNO has better hole transfer and electron barrier ability.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Shang

et al. 2020

ACS Appl. Mater. Interfaces

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In this study, a novel metal oxide, lanthanum nickelate (LNO) with a perovskite structure, was introduced into a polymer solar cell (PSC) device, replacing the PEDOT:PSS hole transport layer (HTL). The results show that the LNO-based PTB7-Th:PC 71 BM solar cell exhibits a higher circuit current density, power conversion efficiency, and stability compared with a device with PEDOT:PSS HTL. To understand the effect of LNO HTL on the performance of devices, the active layer morphology and charge transport characteristics in PSCs were systematically analyzed. The morphology of active layer was affected by the HTL, which further regulated the generation and transport processes of charge carrier in the PSC device. For the LNO HTL, an appropriate thickness (8 nm) and a small surface roughness (S q = 0.7 nm) can coordinate the energy-level structure of device and improve the interface contact between the FTO electrode and PTB7-Th:PC 71 BM active layer, promoting the charge transport performance of device. Therefore, this work provides a new consideration for the preparation of efficient, stable, and low-cost polymer solar cells.

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Section: ■ Results and Discussionmentioning

confidence: 98%

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Shang

et al. 2020

ACS Appl. Mater. Interfaces

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“…For example, charge recombination is quite detrimental to the overall solar cell performance by reducing the short-circuit current and fill factor, and it is mostly linked to bulk heterojunction morphology and carrier mobility. Thus, a more systematic and quantitative study of this problem is important (Araújo et al, 2019). Although the investigation of interfacial morphology and vertical phase segregation is relatively difficult, requiring advanced characterization techniques, it has an important impact on the understanding of device underperformance, so it needs to be further extended.…”

Section: Discussionmentioning

confidence: 99%

Polymer Solar Cells—Interfacial Processes Related to Performance Issues

2019

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Harnessing solar energy with solar cells based on organic materials (in particular polymeric solar cells) is an attractive alternative to silicon-based solar cells due to the advantages of lower weight, flexibility, lower manufacturing costs, easier integration with other products, low environmental impact during manufacturing and operations and short energy payback times. However, even with the latest efficiencies reported up to 17%, the reproducibility of these efficiencies is not up to par, with a significant variation in the efficiencies reported across the literature. Since these devices are based on ultrathin multilayer organic films, interfaces play a major role in their operation and performance. This review gives a concise account of the major interfacial issues that are responsible for influencing the device performance, with emphasis on their physical mechanisms. After an introduction to the basic principles of polymeric solar cells, it briefly discusses charge generation and recombination occurring at the donor-acceptor bulk heterojunction interface. It then discusses interfacial morphology for the active layer and how it affects the performance and stability of these devices. Next, the formation of injection and extraction barriers and their role in the device performance is discussed. Finally, it addresses the most common approaches to change these barriers for improving the solar cell efficiency, including the use of interface dipoles. These issues are interrelated to each other and give a clear and concise understanding of the problem of the underperformance due to interfacial phenomena occurring within the device. This review not only discusses some of the implemented approaches that have been adopted in order to address these problems, but also highlights interfacial issues that are yet to be fully understood in organic solar cells.

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“…onde G é a taxa de geração do estado CT, n e p são as densidades dos portadores gerados pela luz permanente de fundo, n e p são os excessos de carga gerados pela incidência do pulso de Estes resultados estão de acordo com a mudança da mobilidade com a temperatura mostrada na Ref. 89 e corroboram com a hipótese da equação (5.7). No entanto, apesar da discussão acima contribuir para o entendimento dos processos associados ao transporte e recombinação de carga em dispositivos fotovoltaicos BHJ não é suficiente para explicar o comportamento por completo das curvas -RL.…”

Section: Análise Conceitual Das Curvas -Rlunclassified

“…Além da escolha adequada do solvente aditivo para a mistura bifásica, a proporção do aditivo em relação ao solvente principal é outro aspecto importante. Foi utilizado a proporção de 3%v.v por apresentar-se como ideal em dispositivos utilizando os sistemas PCDTBT:PC71BM e PTB7-Th:PC71BM a partir de trabalhos desenvolvidos anteriormente no grupo de pesquisa e resultados reportados na literatura 82,[87][88][89]. Na fabricação dos dispositivos foram utilizados substratos de vidro recobertos com uma fina camada, aproximadamente 120 nm, de óxido de índio dopado com estanho (ITO) obtidos comercialmente da Delta Technologies com resistência de folha de 8-12 Ω/sq.…”

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“…No entanto, esse cálculo é prejudicado pela dificuldade de se obter precisão nas medidas devido ao alto ruído, já que sob diferentes intensidades de iluminação permanente, como mostrado na literatura a mobilidade não deve apresentar dependência com a intensidade de iluminação. No entanto, utilizando o valor de ̅ ≈ 4.0 × 10 −4 cm 2 /V.s, obtido a partir de uma análise da equação de Mott-Gurney (SCLC) para medidas J-V no escuro, com o mesmo tipo de dispositivo aqui usado,89 calculamos 0 ≈ 0,15 ms para extrapolação de RL→ 0, o que é um valor plausível quando comparado com os resultados apresentados na Figura 5.2.…”

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Estudos de propriedades elétricas de dispositivos fotovoltaicos orgânicos: caracterização em regime estacionário e transiente

Cunha¹

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The development of organic solar cells of BHJ type (bulk heterojuntion) has allowed, over the past few years, a significant increase in the power conversion efficiency, thus making closer their use on a large scale. The knowledge of the phenomena that involve the photovoltaic process and its limiting factors are essential factor for the improvement and development of more efficient devices. In this sense, in the present doctoral thesis, the phenomena that govern the generation, transport and recombination of photocarrier were studied, which are responsible for device under operation. For this, initially, photovoltaic optimization and characterization were performed, through J-V stationary measurements and electrical transient measurements, having three different active layers in the BHJ cells: P3HT:PC61BM, PCDTBT:PC71BM e PTB7-Th: PC71BM. Investigations of charge extraction dynamics of and recombination took place mainly through measurements of electrical transients based on the traditional photocurrent transient (TPC) and photovoltaic transient (TPV) techniques. In an equivalent circuit, proposed to explain the measurements, a variable load resistance (RL) was added, acting as a voltage divider with the series resistance (RS) of the device, with which it was possible to cover the entire fourth quadrant of the curve, from the short circuit condition to the open circuit one. With the base line voltage, due to the standing lighting, it was possible to reconstruct the stationary current curve corresponding to the traditional measure with applied voltage (J-V).The electrical transients ∆V(t), obtained under the incidence of the laser pulse, showed monoexponential decay, with which we obtained the relaxation time curves ( ) as a function of the resistance RL of the devices under different conditions of standing lighting, from the dark to 1 Sun (100 mW/cm 2 ). Such measurements were repeated for different temperatures. The curves were divided into three distinct regions. In region I, we identified the domain of extraction of charge carriers; in region II, the competition between the two mechanisms, extraction and recombination; and finally, in region III, the domain of bimolecular recombination. In addition, the -RL curves were analyzed using an equivalent circuit, with which was possible to obtain an analytical expression to describing the entire behavior of the -RL curve. Besides, from the study using a photocurrent analytical model, based on second order recombination kinetics, parameters as the probability of dissociation of the charge transfer state (CT) and the figure of merit θ with temperature were obtained. From this, we analyze the influence of microscopic properties, such as charge carrier mobility and recombination coefficient as the response of the device under lighting.

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Effects of additive-solvents on the mobility and recombination of a solar cell based on PTB7-Th:PC71BM

Cited by 19 publications

References 56 publications

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Polymer Solar Cells—Interfacial Processes Related to Performance Issues

Estudos de propriedades elétricas de dispositivos fotovoltaicos orgânicos: caracterização em regime estacionário e transiente

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Effects of additive-solvents on the mobility and recombination of a solar cell based on PTB7-Th:PC71BM

Cited by 19 publications

References 56 publications

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO3 Layer

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO3 Layer

Polymer Solar Cells—Interfacial Processes Related to Performance Issues

Estudos de propriedades elétricas de dispositivos fotovoltaicos orgânicos: caracterização em regime estacionário e transiente

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Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer