Charge recombination mechanism to explain the negative capacitance in dye-sensitized solar cells

Feng, Lie-Feng; Zhao, Kun; Dai, Haitao; Wang, Shuguo; Sun, Osbert Jianxin

doi:10.1088/1674-1056/25/3/037307

Cited by 6 publications

(3 citation statements)

References 27 publications

(46 reference statements)

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“…In the case of organic semiconductors, it was reported that at higher voltages (∼1 V) the recombination through the interface states is a dominating and it exhibits an inductance like, i.e. the recombination contributes to the negative capacitance [54]. We have also observed similar behavior (decrease in capacitance around 0.6-1.5 V) in the present HgTe NCs/TiO 2 heterostructures.…”

Section: Resultssupporting

confidence: 81%

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction

et al. 2020

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Narrow bandgap (<0.5 eV) colloidal semiconductor nanocrystals (e.g. mercury chalcogenides) provide practical platforms for next generation short wave infrared, mid wave infrared and long wave infrared optoelectronic devices. Until now, most of the efforts in the field of infrared active nanocrystals have been taken on synthesizing nanocrystals, determining quantum states and building different geometries for optoelectronic devices. However, studies on interface trap states in the devices made from these narrow band gap nanocrystals are mostly unexplored. Herein, we investigate the defects or traps in these nanocrystals-embedded devices, which will be critical for improving their optoelectronic performance. In this article, we fabricate HgTe nanocrystals/TiO 2 based photovoltaic devices and used capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) to investigate and obtain quantitative information on deep level trap states. Interestingly, frequency dependent C-V measurements show two peaks in the capacitance at lower frequency (<40 kHz), which is attributed to the presence of trap states. However, at high frequency the presence of a weak hump-like structure almost at the center of above two peaks validate the role of interface traps. DLTS studies show that traps at the interface of HgTe nanocrystals/TiO 2 acts as recombination centers having activation energies of 0.27, 0.4 and 0.45 eV with corresponding trap densities of 1.4 × 10 10 , 1.9 × 10 11 and 1.5 × 10 11 cm −3 and estimated capture cross-sections of 6.3 × 10 −14 , 7.5 × 10 −17 and 3.7 × 10 −14 cm 2 , respectively. In this work, DLTS has revealed the existence of interface trap states and the frequency dependent capacitance measurements corroborate the effect of charge storage on the heterostructures built from these nanocrystals that helps in the development of futuristic devices.

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Section: Resultssupporting

confidence: 81%

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction

et al. 2020

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“… 37 Similar negative capacitance has also been reported by Feng et al in the dye-synthesized solar cell, where the negative capacitance is attributed to the recombination process and chemical capacitance. 40 However, still, it is not known the origin of negative capacitance (NC) in many solar cells. When the UV light incidents on the top surface of the GaN/GaN:N/N:HfO 2 heterostructure, a large amount of photo-charge carriers generated which later recombined with further increase in applied voltage.…”

Section: Resultsmentioning

confidence: 99%

Negative-capacitance and bulk photovoltaic phenomena in gallium nitride nanorods network

et al. 2018

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An enhanced self-powered near-ultraviolet photodetection phenomenon was observed in epitaxial gallium nitride (GaN) nanorods network grown on an intermediate layer of N:GaN on a nitridated HfO 2 (N:HfO 2 )/ SiO 2 /p-Si substrate. The fabricated Au/GaN/N:GaN/N:HfO 2 /Ag heterostructure exhibited a giant change (OFF/ON ratio > 50 without applying any external electrical field) in its conductance when illuminated by a very weak (25 mW cm À2 ) near-UV monochromatic light with a low dark current (nearly 20 nA). The presented near-UV photodetector offers photoresponsivity of $2.4 mA W À1 at an applied voltage of 1 V.We observed an optically generated internal open circuit voltage of $155 mV and short circuit current $430 nA, which can be attributed to the quantum confinement of free charge carriers in the nanorod matrix. Interestingly, it also shows a negative capacitance after near-UV illumination. It has great potential as a self-powered UV photodetector and in metamaterial applications.

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“…[1] Dye-sensitized solar cells (DSCs) have been considered as a promising candidate for large-area practical application due to their low cost, easy fabrication, and considerable efficiency. [2,3] Yet, scaling up the DSCs (larger than 1 cm 2 ) will result in the growth of ohmic losses of the transparent conductive oxide (TCO), since the sheet-resistance (R s > 7 Ω•sq −1 ) of TCO is not negligible in this case. Decline of the fill factor (FF) of the DSCs caused by the increase of ohmic losses needs to be taken into account and mitigated as well.…”

Section: Introductionmentioning

confidence: 99%

Dye-sensitized solar cell module realized photovoltaic and photothermal highly efficient conversion via three-dimensional printing technology

Huang¹,

Zhu²,

Shi³

et al. 2017

Chinese Phys. B

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Three-dimensional (3D) printing technology is employed to improve the photovoltaic and photothermal conversion efficiency of dye-sensitized solar cell (DSC) module. The 3D-printed concentrator is optically designed and improves the photovoltaic efficiency of the DSC module from 5.48% to 7.03%. Additionally, with the 3D-printed microfluidic device serving as water cooling, the temperature of the DSC can be effectively controlled, which is beneficial for keeping a high photovoltaic conversion efficiency for DSC module. Moreover, the 3D-printed microfluidic device can realize photothermal conversion with an instantaneous photothermal efficiency of 42.1%. The integrated device realizes a total photovoltaic and photothermal conversion efficiency of 49% at the optimal working condition.

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Charge recombination mechanism to explain the negative capacitance in dye-sensitized solar cells

Cited by 6 publications

References 27 publications

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction

Negative-capacitance and bulk photovoltaic phenomena in gallium nitride nanorods network

Dye-sensitized solar cell module realized photovoltaic and photothermal highly efficient conversion via three-dimensional printing technology

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Charge recombination mechanism to explain the negative capacitance in dye-sensitized solar cells

Cited by 6 publications

References 27 publications

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO2 heterojunction

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO2 heterojunction

Negative-capacitance and bulk photovoltaic phenomena in gallium nitride nanorods network

Dye-sensitized solar cell module realized photovoltaic and photothermal highly efficient conversion via three-dimensional printing technology

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Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction

Defect studies on short-wave infrared photovoltaic devices based on HgTe nanocrystals/TiO₂ heterojunction