Trap passivation and efficiency improvement of perovskite solar cells by a guanidinium additive

Yao, Jun; Wang, Hui; Wang, Pang; Gurney, Robert S.; Intaniwet, Akarin; Ruankham, Pipat; Choopun, Supab; Liu, Dan; Wang, Tao

doi:10.1039/c9qm00112c

Cited by 29 publications

(28 citation statements)

References 45 publications

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“…This is consistent with the previous report that there is almost no J–V hysteresis for perovskite solar cells using a similar device stack. [ 26 ] Nevertheless, the R–V curves are strongly influenced by scan parameters, showing more significant hysteresis with slower scan rate and with V ( t = 0) = −0.2 V. The different hysteresis behavior in J–V and R–V curves is in line with the larger change in EL intensity than current density, as shown in Figure 1. To give a clearer comparison, we have plotted the J–V (Figure S5, Supporting Information) and R–V (Figure S6, Supporting Information) curves separately both in linear and semi‐log scales.…”

Section: Figurementioning

confidence: 74%

Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis

Elkhouly

Gehlhaar

Genoe

et al. 2020

Advanced Optical Materials

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However, due to the transient effects that are, to a large extent, a result of the ionic nature of perovskite materials, the characterization of perovskite optoelectronic devices is often sensitive to the applied measurement protocols. [11,12] This makes it difficult to compare and reproduce the reported device characteristics from different research groups, especially when the protocols are not well described. In the case of perovskite solar cells, it has been shown that the anomalous hysteresis effect, which is highly dependent on the voltage scan rate, range, direction, as well as the device structure, could significantly influence current density-voltage (J-V) characteristics and the reported power conversion efficiency (PCE) value. [13] This has triggered intensive studies on the origin of the device hysteresis and wide discussions on how to report the perovskite solar cell characteristics, leading to clear standards that are broadly followed by the perovskite photovoltaic field. [14] However, much less attention was given to the sensitivity of PeLED characteristics to their measurement protocols, which urged a discussion about the standardization of measurement procedures, and about the best practices for characterization. [15] For PeLEDs, the current density-voltage-radiance/luminance (J-V-R/L), and the EQE-J characteristics are the main figures of merit. Although the hysteresis in J-V characteristics is to date well-understood and attributed to ion migration and interfacial charge trapping, [16-18] the influence of these transient effects and device hysteresis on the PeLED performances lacks investigation. Zhao et al. have shown that under electrical stress, PeLEDs showed an EQE enhancement accompanied by a reduction in the diode ideality factor. [19] This phenomenon was attributed to trap filling by excess ions which reduces nonradiative recombination. It can be observed in many PeLEDs in literature during lifetime measurements, with the stressing time spanning a wide range of timescales from few minutes to several hours. [8,20,21] In this report, we show that the electroluminescence (EL) intensity of PeLEDs changes significantly even on a timescale from 100 ms to a few seconds. Such reversible EL transients, together with the possible device degradation during measurement, could lead to severe device hysteresis, making the reported J-V-R/L and EQE-J curves highly dependent on measurement protocols. Moreover, we show that a method based on pulsed excitation with cooldown time in-between The reproducibility of results is one of the cornerstones of scientific research. However, in emerging technologies, the reported results often tend to be sensitive to the chosen measurement protocol. This can stem from measurement artifacts or from unknown complex underlying phenomena. Metal halide perovskites have emerged as an exciting material system for optoelectronic devices. The anomalous hysteresis in the current density-voltage (J-V) characteristics of perovskite solar cells has triggered wide discussions on how ...

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Section: Figurementioning

confidence: 74%

Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis

Elkhouly

Gehlhaar

Genoe

et al. 2020

Advanced Optical Materials

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“…The upward shift of the VBM of the 2 mg PEAI deposited sample improves its energy band alignment with that of the HTL, Spiro‐OMeTAD, potentially contributing to the reduced voltage losses compared to the reference sample (see Figure c). [ 30 ]…”

Section: Resultsmentioning

confidence: 99%

Enhanced Hole‐Carrier Selectivity in Wide Bandgap Halide Perovskite Photovoltaic Devices for Indoor Internet of Things Applications

Lee

Choi

Soufiani

et al. 2021

Adv Funct Materials

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Halide perovskite‐based photovoltaic (PV) devices have recently emerged for low energy consumption electronic devices such as Internet of Things (IoT). In this work, an effective strategy to form a hole‐selective layer using phenethylammonium iodide (PEAI) salt is presented that demonstrates unprecedently high open‐circuit voltage of 0.9 V with 18 µW cm−2 under 200 lux (cool white light‐emitting diodes). An appropriate post‐deposited amount of PEAI (2 mg) strongly interacts with the perovskite surface forming a conformal coating of PEAI on the perovskite film surface, which improves the crystallinity and absorption of the film. Here, Kelvin probe force microscopy results indicate the diminished potential difference across the grain boundaries and grain interiors after the PEAI deposition, constructing an electrically and chemically homogeneous surface. Also, the surface becomes more p‐type with a downshift of a valence band maximum, confirmed by ultraviolet photoelectron spectroscopy measurement, facilitating the transport of holes to the hole transport layer (HTL). The hole‐selective layer‐deposited devices exhibit reduced hysteresis in light current density–voltage curves and maintain steadily high fill factor across the different light intensities (200–1000 lux). This work highlights the importance of the HTL/perovskite interface that prepares the indoor halide perovskite PV devices for powering IoT device.

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“…Recent studies have reported that GUA cation can form strong hydrogen bonds with the halides that may passivate the defects and improve the device performance. [46,47] The capacitance response of MAPbI 3 and MAGUA devices depicts the similar frequency response in the low-and high-frequency regions, but C LF increases significantly as bias approaches to V OC for MAGUA PSC (see for more detail in the study by Kubicki et al [45] ). In line with the results on IPA-treated PSCs, we also found that a higher value of C LF not necessary leads to higher recombination.…”

Section: Effect Of Perovskite Composition On the Low-frequency Arc In Eis Of Pscmentioning

confidence: 93%

In the Quest of Low‐Frequency Impedance Spectra of Efficient Perovskite Solar Cells

et al. 2021

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Measurement and understanding of electrochemical impedance spectroscopy of perovskite solar cells (PSCs) are nontrivial, as perovskite absorbers are a mixed conductor exhibiting both ionic and electronic motion. Moreover, the interpretation of the low-frequency spectra especially low-frequency resistance (R LF ) is ambiguous. Some reports suggest that R LF is related to ionic transport resistance, whereas others attribute it with the recombination processes. Herein, more light is put on the quest of low-frequency impedance spectra of efficient PSCs. It is found that high-and low-frequency resistances (R HF and R LF ) follow a similar dependence on the applied bias and illumination with a comparable slope. These resistances are associated with the recombination processes in PSCs. The relation between low-frequency spectra of PSCs and the physical parameters such as the role of the interface, grains' sizes, and perovskite composition is studied. It is found that the low-frequency spectra of PSCs mainly depend on the grains' sizes and shift toward the high frequency, i.e., toward faster time constants with increasing the grain size. It is observed that these devices exhibit the lower recombination and higher open-circuit voltage. A convenient way for the in-depth analysis of PSCs, which will be crucial for designing better-performing PSCs, is provided.

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Trap passivation and efficiency improvement of perovskite solar cells by a guanidinium additive

Cited by 29 publications

References 45 publications

Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis

Perovskite Light Emitting Diode Characteristics: The Effects of Electroluminescence Transient and Hysteresis

Enhanced Hole‐Carrier Selectivity in Wide Bandgap Halide Perovskite Photovoltaic Devices for Indoor Internet of Things Applications

In the Quest of Low‐Frequency Impedance Spectra of Efficient Perovskite Solar Cells

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