ORCID Profile
0000-0001-6143-9322
Current Organisations
Charles Darwin University
,
Indian Institute of Technology Delhi
,
Indian Institute of Technology Kanpur
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Publisher: MDPI AG
Date: 27-06-2019
DOI: 10.20944/PREPRINTS201906.0281.V1
Abstract: In this paper, by developing a mathematical model, the operating temperature of perovskite solar cells (PSCs) under different operating conditions has been calculated. It is found that by reducing the density of tail states at the interfaces, acting as recombination centres, through some passivation mechanisms, the operating temperature can be reduced significantly at higher applied voltages. The results show that if the density of tail states at the interfaces is reduced by three orders of magnitude through some passivation mechanisms, then the active layer may not undergo any phase change up to an ambient temperature 300 K and it may not degrade up to 320 K. The calculated heat generation at the interfaces at different applied voltages with and without passivation shows that the heat generation can be reduced by passivating the interfaces. It is expected that this study may provide a deeper understanding of the influence of interface passivation on the operating temperature of PSCs.
Publisher: MDPI AG
Date: 03-10-2017
Publisher: Wiley
Date: 29-07-2021
Abstract: A comprehensive study of the operating temperature () of three nonfullerene (NF) acceptor‐based bulk heterojunction organic solar cells (BHJ OSCs), two conventional (OSC1 and OSC3) and one inverted (OSC2) structure, is presented. A quantitative analysis of the thermal power generated by photon absorption in transport layers and electrodes, thermalization of photoexcited charge carriers, tail‐state recombination, and resistive heating is conducted. For all three OSCs, the dependence of operating temperature on the voltage is simulated and it is found that OSC1 and OSC2 operate at about 320 K and OSC3 at 319 K. It is also found that the thermal power generated due to thermalization ( P T ) and absorption in other than the active layer () in OSC3 are smaller than those in both OSC1 and OSC2 but the thermal power generated due to the resistive heating ( P R ) is larger in OSC3 than in OSC1 and OSC2, leading to the net power absorbed in the active layer of OSC3 being higher than that in OSC1 and OSC2. Thus, although the operating temperature of all three cells remains in the range from 320 to 321 K, OSC3 shows a better photovoltaic performance.
Publisher: AIP Publishing
Date: 24-08-2018
DOI: 10.1063/1.5031062
Abstract: Applying the optical transfer matrix method and the drift-diffusion equations, the efficient light absorption, exciton generation, and recombination rate in bulk heterojunction (BHJ) organic solar cells (OSCs) with conventional and inverted configurations are studied. Analysing the influence of the electric field component of the electromagnetic radiation propagating through the layered structure of BHJ OSCs and using contour plots of normalized modulus squared of the electric field, the constructive interference points (CIPs) which represent the positions of maximum absorption of photons and hence generation of excitons within the active layer are investigated for both the conventional and inverted OSCs. Also, the influence of the thicknesses of other layers in both the inverted and conventional structures is investigated. It is found that except the thickness of MoO3 in the inverted structure the thicknesses of other layers do not have any significant influence on CIPs. The maximum CIP occurs at an active layer thickness of 190 nm, regardless of the thickness of the second layer, which is MoO3, Ag, or ITO in the inverted structure and PEDOT:PSS, Al, or ITO in the conventional structure. The results of 3D plots of the normalized modulus squared of the electric field reveal that the absorption of photons at the end of the active layer in the inverted structure is higher than that in the conventional structure for all the effective wavelengths and different active layer thicknesses. It is expected that this study provides a deeper understanding of exciton generation within the two structures.
Publisher: AIP Publishing
Date: 21-12-2020
DOI: 10.1063/5.0028266
Abstract: Analytical expressions for the effective mass of heavy, light, and spin split-off electrons are obtained by diagonalizing the k⋅p Hamiltonian for cubic perovskite crystal structures and used to calculate these in nine perovskite materials. An expression for the effective hole g-factor is also derived and calculated in these perovskites. The calculated effective mass of heavy electrons ranges from 1.619 m0 to 0.201 m0, of light electrons from 0.357 m0 to 0.146 m0, and of spin split-off electrons from 0.584 m0 to 0.169 m0. It is found that Cl- and Pb-based perovskite materials have larger heavy, light, and spin split-off electron effective masses. It is also found that the effective g-factor increases with the atomic size, from Cl to I, for the series CsSnX3(X=Cl,Br,I).
Publisher: MDPI AG
Date: 19-01-2022
DOI: 10.3390/EN15030711
Abstract: Using the optical transfer matrix method, we optimized the layered structure of a conventional and an inverted BHJ OSC with the active layer made of blended PTB7-Th:PNDI-T10 by maximizing the optical absorption and, hence, the JSC. The maximum JSC thus obtained from the optimised structure of the inverted OSC was 139 Am−2 and that of the conventional OSC was 135 Am−2. Simulation of the electric field distribution in both inverted and conventional OSCs showed that the formation of a single CIP was obtained in the active layer of thickness 105 nm in both OSCs. As the light incidents from the ITO side, it was found that excitons were generated more closely to ITO electrode, which favors the efficient charge transport and collection at the opposite electrodes in the inverted OSC, which produces higher JSC.
Publisher: American Chemical Society (ACS)
Date: 29-06-2022
Publisher: Wiley
Date: 02-11-2021
Publisher: Springer Science and Business Media LLC
Date: 19-07-2017
Publisher: Springer Science and Business Media LLC
Date: 14-05-2019
Publisher: Springer Science and Business Media LLC
Date: 18-06-2018
Publisher: Springer Science and Business Media LLC
Date: 05-09-2022
Publisher: Wiley
Date: 31-03-2023
Abstract: In this paper, a mathematical model and the relevant computer code are developed to quantify the extraction probability rate of charge carriers (EPRCC) in a perovskite solar cell of the structure: Glass/ITO/PEDOT: PSS/CH 3 NH 3 PbI 3 /PC 60 BM/Al to investigate the influence of interfaces and grain boundaries. It is found that, without passivation, the probability of an electron generated near the anode reaches to the cathode is only 35%, while by passivating the interfaces and grain boundaries, this probability increases to about 60% at maximum power point condition. Likewise, without passivation, the probability of a hole generated near the electron transport layer‐active layer interface reaches to the hole transport layer is only 15%, while by passivating the interfaces and grain boundaries, this probability increases to about 45% at maximum power point condition. The same calculation has been done at the short‐circuit current condition, and it is found that at the maximum power point condition, passivation works better for increasing the EPRCC than at the short circuit current condition. The authors have also investigated the influence of grain boundary sizes on the EPRCC, and the results show that the EPRCC is almost grain boundary size independent.
Publisher: Wiley
Date: 09-04-2019
Publisher: Wiley
Date: 10-10-2023
Abstract: A new analytical expression that directly relates the open‐circuit voltage ( V oc ) in perovskite solar cells (PSCs) to the quasi‐Fermi level splitting (QFLS), interface energy offsets, and nonradiative recombination losses has been derived. It is found that the QFLS of the active layer plays a dominant role in enhancing V oc of PSCs. The newly derived V oc is applied to two PSCs with the hole transport layer (HTL) of poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine], and poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and found that the first PSC has a higher V oc , which agrees well with the experimental results. It is found that both PSCs exhibit saturation of V oc at the higher charge carrier generation rates and hence at higher light intensities. The lower V oc in PSC with P3HT as HTL is attributed to the stronger band bending and higher interfacial defects. In accordance with the results, a large quasi‐Fermi level splitting and a minimal interfacial energy offsets may be considered when selecting material for high V oc PSCs.
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 21-08-2017
Abstract: What motivates corporate political action? Are corporations motivated by their own narrow economic self-interest are they committed to pursuing larger class interests or are corporations instruments for status groups to pursue their own agendas? Sociologists have been ided over this question for much of the last century. This paper introduces a novel case - that of Australia - and an extensive dataset of over 1,500 corporations and 7,500 directors. The paper attempts to understand the motives of corporate political action by examining patterns of corporate political donations. Using statistical modelling, supported by qualitative evidence, the paper argues that, in the Australian case, corporate political action is largely motivated by the narrow economic self-interest of in idual corporations. Firms' interests are, consistent with regulatory environment theory, defined by the nature of government regulation in their industry: those in highly regulated industries (such as banking) and those dependent on government support (such as defence) tend to adopt a strategy of hedging their political support, and make bipartisan donations (to both major parties). In contrast, firms facing hostile regulation (such as timber or mining), and those without strong dependence on state support (such as small companies) tend to adopt a strategy of conservative partisanship, and make conservative-only donations. This paper argues that regulatory environment theory needs to be modified to incorporate greater emphasis on the subjective political judgements of corporations facing hostile regulation: a corporation's adoption of conservative partisanship or hedging is not just a product of the objective regulation they face, but also whether corporate leaders judge such regulation as politically inevitable or something that can be resisted. Such a judgement is highly subjective, introducing a dynamic and unpredictable dimension to corporate political action.
Publisher: Wiley
Date: 10-05-2020
Publisher: Wiley
Date: 07-02-2019
Publisher: Springer Science and Business Media LLC
Date: 14-02-2017
Publisher: MDPI AG
Date: 26-08-2019
DOI: 10.3390/MA12172727
Abstract: In this paper, by developing a mathematical model, the temperature of PSCs under different operating conditions has been calculated. It is found that by reducing the density of tail states at the interfaces through some passivation mechanisms, the operating temperature can be decreased significantly at higher applied voltages. The results show that if the density of tail states at the interfaces is reduced by three orders of magnitude through some passivation mechanisms, then the active layer may not undergo any phase change up to an ambient temperature 300 K and it may not degrade up to 320 K. The calculated heat generation at the interfaces at different applied voltages with and without passivation shows reduced heat generation after reducing the density of tail states at the interfaces. It is expected that this study provides a deeper understanding of the influence of interface passivation on the operating temperature of PSCs.
Publisher: MDPI AG
Date: 27-01-2022
DOI: 10.3390/NANO12030420
Abstract: Thermal stability, closely associated with the operating temperature, is one of the desired properties for practical applications of organic solar cells (OSCs). In this paper, an OSC of the structure of ITO/PEDOT:PSS/P3HT:PCBM/ZnO/Ag was fabricated, and its current-voltage (J-V) characteristics and operating temperature were measured. The operating temperature of the same OSC was simulated using an analytical model, taking into consideration the heat transfer, charge carrier drift-diffusion and different thermal generation processes. The simulated results agreed well with the experimental ones. It was found that the thermalization of charge carriers above the band gap had the highest influence on the operating temperature of the OSCs. The energy off-set at the donor/acceptor interface in the bulk heterojunction (BHJ) was shown to have a negligible impact on the thermal stability of the OSCs. However, the energy off-sets at the electrode/charge-transporting layer and BHJ/charge-transporting layer interfaces had greater impacts on the operating temperature of OSCs at the short circuit current and maximum power point conditions. Our results revealed that a variation over the energy off-set range from 0.1 to 0.9 eV would induce an almost 10-time increase in the corresponding thermal power generation, e.g., from 0.001 to 0.01 W, in the cells operated at the short circuit current condition, contributing to about 16.7% of the total solar power absorbed in the OSC.
Publisher: Springer Science and Business Media LLC
Date: 23-11-2016
Publisher: Wiley
Date: 03-03-2019
Publisher: MDPI AG
Date: 15-01-2021
DOI: 10.3390/NANO11010209
Abstract: In this paper, characterisation of exciton generation is carried out in three bulk-heterojunction organic solar cells (BHJ OSCs)—OSC1: an inverted non-fullerene (NF) BHJ OSC OSC2: a conventional NF BHJ OSC and OSC3: a conventional fullerene BHJ OSC. It is found that the overlap of the regions of strong constructive interference of incident and reflected electric fields of electromagnetic waves and those of high photon absorption within the active layer depends on the active layer thickness. An optimal thickness of the active layer can thus be obtained at which this overlap is maximum. We have simulated the rates of total exciton generation and position dependent exciton generation within the active layer as a function of the thicknesses of all the layers in all three OSCs and optimised their structures. Based on our simulated results, the inverted NF BHJ OSC1 is found to have better short circuit current density which may lead to better photovoltaic performance than the other two. It is expected that the results of this paper may provide guidance in fabricating highly efficient and cost effective BHJ OSCs.
Publisher: AIP Publishing
Date: 16-10-2019
DOI: 10.1063/1.5118261
Abstract: We have developed a model to calculate the temperature of an illuminated perovskite solar cell (PSC) under the forward bias and that of a shaded one under the reverse bias at different ambient conditions. The results show that the dissipated power due to the reverse bias (PRB) should be more than around 6 W to have a higher temperature in the shaded solar cell than that in the illuminated solar cell at the solar irradiance of 1000W/m2, and this result is almost ambient temperature and wind velocity independent. It is also found that the generated thermal power due to the nonradiative recombination (PRec) becomes significant at the open circuit voltage (Voc) condition, leading to illuminated solar cell temperature (Tcr) higher than that at the short circuit current (Jsc) condition by about 12.7 K, 13.3 K, and 13.9 K at the ambient temperatures of 270 K, 300 K, and 330 K, respectively. In addition, the influence of the thickness of the illuminated solar cell on its temperature at the Voc condition is investigated, which reveals that, by increasing the thickness from 100 nm to 300 nm, the solar cell temperature can increase by 20 K.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Springer Science and Business Media LLC
Date: 06-02-2017
No related grants have been discovered for Małgorzata Tokarska.