Low‐Dimensional Contact Layers for Enhanced Perovskite Photodiodes

Luo, Deying; Zou, Taoyu; Yang, Wengqiang; Xiang, Beng; Yang, Xiaoyu; Ya, Wang; Su, Rui; Zhao, Lichen; Zhu, Rui; Zhou, Hang; Russell, Thomas P.; Yu, Hongyu; Lu, Zheng‐Hong

doi:10.1002/adfm.202001692

Cited by 38 publications

(32 citation statements)

References 38 publications

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“…[17,116] When the resultant strain belongs to tensile strain, the non-radiative recombination losses, and the subsequent decrease of device performance could be accelerated. [30] Our recent work has demonstrated that inserting a bottom buffer layer can mediate the lattice strain of perovskite films whilst modulating structural defects and crystallization, [117] resulting in improved band alignment. To be more specific, by inserting a pre-coating layer of large organic molecules before the perovskite deposition, low-dimensional contacts would be formed at the bottom side of final perovskite films (Figure 7a).…”

Section: Surface Buffer Materials For Growing Better Perovskitesmentioning

confidence: 99%

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

et al. 2021

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conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) have already surpassed 25%, [4] which is comparable to current industrial-grade mono-crystalline silicon solar cells. This fantastic efficiency combined with potentially low-cost fabrication makes them more attractive than the most efficient photovoltaic technologies. [5] Similarly, perovskite light-emitting diodes (PeLEDs) are shown to have an extraordinary performance with external quantum efficiencies (EQEs) exceeding 20% in devices made from the solution phase at low temperatures. [6][7][8] We associated these notable improvements on device performance with lessons learned from organic optoelectronics and other semiconductor devices. Typically, many empirical approaches learned from others such as structural optimization, [9] interface engineering, [10] defects passivation, [11] etc., have been considered optimizing the carrier injection/extraction and mitigating undesirable non-radiative recombination losses. [12][13][14][15][16] Nonetheless, there is plenty of room optimizing nonradiative recombination losses in the bulk and at the interfaces to reach the efficiency limits. [17,18] Historically, band misalignments and interfacial defects have been considered the predominant factors responsible for the undesirable recombination at the various interfaces in devices. [19][20][21] In light of band misalignment, the resulting nonradiative recombination losses at the perovskite interfaces cause a substantial reduction in open-circuit voltages (V oc ) of the PeSCs, [14] mainly because of charge extraction suppression. For example, an energy barrier height of >0.1 eV is sufficient to block the extraction of majority carriers and to block the minority carriers from entering the undesirable transport layer, resulting in efficiency losses. [22] The presence of a charge injection barrier is also known to impact the turn-on voltage and device efficiency of PeLEDs. [23] Moreover, the deep-level defect-assisted recombination provides an additional path for intrinsic loss of charge carriers. [24][25][26] However, the origin and distribution of deep-level defects, a kind of defect that are far away from the band edge and can trap charge carriers, are highly debated topics. To date, there are several experimental observations confirming that a considerable density of deep-level defects retains at the interfaces of both the single-crystal and polycrystalline devices, and some surface passivation strategies can considerably eliminate the defects on the surfaces. [27][28][29] Based on photoemission Surfaces and heterojunction interfaces, where defects and energy levels dictate charge-carrier dynamics in optoelectronic devices, are critical for unlocking the full potential of perovskite semiconductors. In this progress report, chemical structures of perovskite surfaces are discussed and basic physical rules for the band alignment are summarized at various perovskite interfaces. Common perovskite surfaces are typically decorated by various compositional and structur...

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Section: Surface Buffer Materials For Growing Better Perovskitesmentioning

confidence: 99%

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

et al. 2021

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“…Over the last decade, perovskite photovoltaics (PPV) have shown dramatic achievements in both the device efficiency and long-term stability 1 – 7 . Despite notable advances in the device performance, there is still a certain gap between the record power conversion efficiencies (PCEs) and the theoretical limit defined by the Shockley-Queisser theory.…”

Section: Introductionmentioning

confidence: 99%

Dielectric screening in perovskite photovoltaics

et al. 2021

Nat Commun

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The performance of perovskite photovoltaics is fundamentally impeded by the presence of undesirable defects that contribute to non-radiative losses within the devices. Although mitigating these losses has been extensively reported by numerous passivation strategies, a detailed understanding of loss origins within the devices remains elusive. Here, we demonstrate that the defect capturing probability estimated by the capture cross-section is decreased by varying the dielectric response, producing the dielectric screening effect in the perovskite. The resulting perovskites also show reduced surface recombination and a weaker electron-phonon coupling. All of these boost the power conversion efficiency to 22.3% for an inverted perovskite photovoltaic device with a high open-circuit voltage of 1.25 V and a low voltage deficit of 0.37 V (a bandgap ~1.62 eV). Our results provide not only an in-depth understanding of the carrier capture processes in perovskites, but also a promising pathway for realizing highly efficient devices via dielectric regulation.

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“…However, even in photodiode devices with charge transport materials to suppress carrier injection form the electrode, most polycrystalline perovskite detectors still suffer from unacceptably large dark current. It was highlighted that the undesired interfacial energy barrier that incapable of completely blocking carrier injection at high electrical field is known as a main reason for the large dark current 109 . Meanwhile, thermally activated carrier injection via the defect states within the bandgap could also lead to a large dark current in a photodiode type detector 64 .…”

Section: Discussionmentioning

confidence: 99%

“…main reason for the large dark current. 109 Meanwhile, thermally activated carrier injection via the defect states within the bandgap could also lead to a large dark current in a photodiode type detector. 64 Nonetheless, the origin of the high dark current remains to be an open question, which require further investigations.…”

Section: T a B L E 3 Key Parameters Of Polycrystalline Perovskites Bamentioning

confidence: 99%

Halide perovskites: A dark horse for direct X‐ray imaging

Qian

Xiao

et al. 2020

EcoMat

118

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The high cost and difficulty of fabricating high-quality, thick, large-area X-ray absorbers limit their widespread applications in flat-panel direct hard X-ray imaging. Then it comes to the recently rising halide perovskites, which show large carrier mobility and lifetime, contain high atomic number elements and are solution processible, making them ideal for large-area direct hard X-ray imaging. Over the past few years, direct X-ray detectors based on a variety of perovskites have been developed, showing impressive progress in achieving high sensitivity and low detection limit. Alongside the developments, the underlying correlations between the intrinsic properties of the perovskites and their X-ray detection performance have been intensively studied, providing valuable information to tackle the remaining challenges, such as large dark current, baseline drifting and so forth. However, it is surprising to find that there have been no efforts to bring together a comprehensive review and comparative analysis on these previous research endeavors, and some general principles and guidelines of engineering the perovskites toward advanced X-ray detectors have yet to be creamed off. Here, recent advances in engineering perovskites for direct X-ray detection are reviewed in the hope of providing fundamental understanding of this fast-developing field. First, the operation principles of direct X-ray detectors targeting flat-panel X-ray imaging will be introduced, particularly relevant to perovskite materials. Then, recent innovative works regarding the preparation and manipulation of single-crystalline and poly-crystalline perovskites are discussed in detail, through which specific effects of the intrinsic properties of the perovskite upon X-ray detection are highlighted. This is followed by a summary of the review and outlook of future directions.

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Low‐Dimensional Contact Layers for Enhanced Perovskite Photodiodes

Cited by 38 publications

References 38 publications

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Recent Progress on Perovskite Surfaces and Interfaces in Optoelectronic Devices

Dielectric screening in perovskite photovoltaics

Halide perovskites: A dark horse for direct X‐ray imaging

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