Modulated electroluminescence technique for determination of the minority carrier lifetime of solar cells

Khatavkar, Sanchit; M, Kulasekaran; Kannan, C. Ramesh; Kumar, Vijay; Nair, Pradeep R.; Arora, B. M.

doi:10.1109/pvsc.2013.6744230

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…The fabrication details of the sample are provided in [30]. The capacitance measurements are carried out using HP 4194A impedance/gainphase analyzer.…”

Section: Key Parameter Extractionmentioning

confidence: 99%

Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Chavali

Khatavkar

Kannan³

et al. 2015

IEEE J. Photovoltaics

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The performance of modern a-Si/c-Si heterojunction (HIT) solar cells is dictated by a complex interplay of multiple device parameters. A single characterization experiment [e.g., light current-voltage (I-V)] can be fitted with a set of parameters, but this set may not be unique and is, therefore, questionable as the basis for future design/optimization. In this paper, we use multiple (quasi-orthogonal) measurement techniques to uniquely identify the key parameters that dictate the performance of HIT cells. First, we study the frequency, voltage, and temperature response of inversion charge (Q Inv ) to create the theoretical basis for characterization of key device parameters, namely, the thickness of the i-layer at the front interface (t i a −S i ), a-Si/c-Si heterojunction valence band discontinuity (ΔE V ), built-in potentials in a-Si (φ a −S i ) and c-Si (φ c −S i ) regions, etc. Next, we simulate various characterization measurements, such as capacitance-voltage (C-V) and impedance spectroscopy, which probe Q Inv and explain the parameter extraction procedure from these measurements. Subsequently, we use the algorithm/procedure just developed to extract the aforementioned parameters for an industrial-grade HIT sample. Finally, we extend this quasi-orthogonal characterization framework by correlating the C-V characteristics with the ubiquitous light and dark I-V characteristics to demonstrate the consistency of the developed theory and uniqueness of the parameter extracted. The unique parameter set thus obtained can simultaneously provide a basis for the interpretation of the experimental measurements and can also be used for the design/optimization of these solar cells.

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“…The fabrication details of the sample are provided in [30]. The capacitance measurements are carried out using HP 4194A impedance/gainphase analyzer.…”

Section: Key Parameter Extractionmentioning

confidence: 99%

Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Chavali

Khatavkar

Kannan³

et al. 2015

IEEE J. Photovoltaics

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“…[30] This methodology will be especially useful when the radiative recombination event is convoluted with previous electronic carrier steps such as transport, trapping, or contact polarization effects, and/or ionic-related phenomena. It has previously been remarked that the capacitance and luminance of LEDs show correlated features [21,31,32] and some studies of electrically stimulated light emission spectroscopy have been reported, [33][34][35] but unfortunately, a general methodology has not been fully developed.Here we describe the first LEVS experiments in halide perovskite LEDs and establish an equivalent circuit model to understand the observed spectra, based on the previous experience in IS. We show that the method provides unique information on the recombination processes that cannot be accessed by purely electrical techniques, thus highlighting the interest of this new experimental technique for the characterization of optoelectronic devices, especially those presenting multiple physical phenomena, as it is the case of halide perovskite-based systems.…”

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Radiative Recombination Processes in Halide Perovskites Observed by Light Emission Voltage Modulated Spectroscopy

et al. 2023

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and discharge of the carriers at the contact layers; [12,[25][26][27] however, these phenomena are currently not very well understood.The light emission kinetics in perovskite LEDs and in organic light-emitting diodes (OLEDs) is usually investigated using a range of steady-state and timeresolved methods. [26,28] Remarkably, frequency-resolved methods such as impedance spectroscopy (IS) are highly effective for the separation of concomitant kinetic phenomena. [29] The connection between time transients and light-stimulated frequency methods in halide perovskite has been reviewed recently. [30] Here, we explore a new experimental measuring technique that can provide significant information about recombination in high-performance solar cells and LEDs. We analyze the frequency-resolved light emission with respect to an applied modu lated voltage, that we denote light emission voltage modulated spectroscopy (LEVS). The main point of this investigation is to reveal significant features of the radiative charge recombination that are difficult to be discerned in other measurement techniques. [30] This methodology will be especially useful when the radiative recombination event is convoluted with previous electronic carrier steps such as transport, trapping, or contact polarization effects, and/or ionic-related phenomena. It has previously been remarked that the capacitance and luminance of LEDs show correlated features [21,31,32] and some studies of electrically stimulated light emission spectroscopy have been reported, [33][34][35] but unfortunately, a general methodology has not been fully developed.Here we describe the first LEVS experiments in halide perovskite LEDs and establish an equivalent circuit model to understand the observed spectra, based on the previous experience in IS. We show that the method provides unique information on the recombination processes that cannot be accessed by purely electrical techniques, thus highlighting the interest of this new experimental technique for the characterization of optoelectronic devices, especially those presenting multiple physical phenomena, as it is the case of halide perovskite-based systems. The Transfer Functions of Frequency Resolved Measurements IS is a general-purpose characterization technique that is used in a large variety of fields to extract dynamic information on anyThe kinetics of light emission in halide perovskite light-emitting diodes (LEDs) and solar cells is composed of a radiative recombination of voltage-injected carriers mediated by additional steps such as carrier trapping, redistribution of injected carriers, and photon recycling that affect the observed luminescence decays. These processes are investigated in high-performance halide perovskite LEDs, with external quantum efficiency (EQE) and luminance values higher than 20% and 80 000 Cd m −2 , by measuring the frequency-resolved emitted light with respect to modulated voltage through a new methodology termed light emission voltage modulated spectroscopy (LEVS). The spectra are shown to provid...

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A critical analysis on the role of back surface passivation for a-Si/c-Si heterojunction solar cells

Chatterji

Khatavkar

Voz

et al. 2014

2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)

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Back surface passivation is a well-known method to reduce carrier recombination and hence improves the efficiency of crystalline silicon solar cells. In this manuscript, we critically analyze the role of this process for a-Si/c-Si heterojunction solar cells through a combination of device fabrication, multiple characterization techniques, and modeling. Curiously, our experimental results indicate that dark current characteristics of these devices do not scale in accordance with the improvements in carrier lifetime achieved through back surface passivation. Our results indicate these puzzling experimental results could be due to the possibility that carrier injection from crystalline silicon base significantly contributes to the dark current of these devices. This result has obvious and significant implications towards understanding the device physics and efficiency optimization of a-Si/c-Si heterojunction devices.Peer ReviewedPostprint (published version

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Modulated electroluminescence technique for determination of the minority carrier lifetime of solar cells

Cited by 5 publications

References 5 publications

Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Multiprobe Characterization of Inversion Charge for Self-Consistent Parameterization of HIT Cells

Radiative Recombination Processes in Halide Perovskites Observed by Light Emission Voltage Modulated Spectroscopy

A critical analysis on the role of back surface passivation for a-Si/c-Si heterojunction solar cells

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