Effects of Transition Metal Substituents on Interfacial and Electronic Structure of CH3NH3PbI3/TiO2 Interface: A First-Principles Comparative Study

Xue, Yuanbin; Li, Xian Chang; Li, Chengbo; Song, Haixiang; Niu, Yongsheng; Liu, Hu; Mai, Xianmin; Zhang, Jiaoxia; Guo, Zhanhu

doi:10.3390/nano9070966

Cited by 18 publications

(7 citation statements)

References 69 publications

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“…APbX 3 (A = Cs, methylammonium(MA), formadamidinium (FA): X = I, Br, Cl) lead halide perovskites belong to a class of materials that have shown promise for high efficiency LEDs − and photovoltaics. − It is interesting to note that PV efficiency can be tuned by morphology control of radiative recombination − and interfacial engineering. − Scanning tunneling microscopy (STM) experiments of lead halide perovskite help provide a more complete picture of these materials …”

Section: Introductionmentioning

confidence: 99%

Spectral Signatures of Positive and Negative Polarons in Lead-Halide Perovskite Nanocrystals

2019

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APbX 3 (A = Cs, methylammonium {MA}; X = I, Br, Cl) lead halide perovskites are of interest for light-emitting applications due to the tunability of their bandgap across the visible and near-infrared spectrum (IR) coupled with efficient photoluminescence quantum yields (PLQYs). It is widely speculated that photoexcited electrons and holes spatially separate into large (Frolich) negative and positive polarons which are stabilized by the A cations. Polarons are expected to be optically active, with recent IR transient absorption experiments showing spectral features consistent with photoionization of the polaron into the continuum band states. For large polarons in the intermediate coupling regime, it would also be expected to observe spectral signatures of transitions within the polaronic potential well producing polaron excited-states. From the polaron excited-state we predict that large polarons should be capable of spontaneous emission (photoluminescence) in the mid-IR to far-IR regime based on the concept of inverse occupations within the polaron potential well. To test this hypothesis, we use density-functional theory (DFT) based calculations using a CsPbBr 3 nanocrystal atomistic model as a host material for either negative (electron) or positive (hole) polarons. We dynamically couple electronic and nuclear degrees of freedom by computing nonadiabatic couplings which allow us to explore nonradiative relaxation of excited polaronic states. Radiative relaxation of excited polaronic states is found from Einstein coefficients for spontaneous emission. Efficiency of polaron emission is determined from rates of nonradiative recombination (k NR ) and radiative recombination (k R ) as k R /(k R + k NR ). It is found that both the positive and negative polaron show bright absorption features and photoluminescence from the relaxed-excited state (RES) to the polaron ground states (PGS), but it is an inefficient process (PLQY ∼ 10 −4 −10 −7 ). Methodology considerations for improving the computed PLQY of polaron emission are discussed, such as Marcus rate corrections and coherence. This work provides computational support for observation of IR polaron absorption and a potential direction toward extending the emission capabilities of APbX 3 perovskites into the mid-IR to far-IR regime.

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Section: Introductionmentioning

confidence: 99%

Spectral Signatures of Positive and Negative Polarons in Lead-Halide Perovskite Nanocrystals

2019

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“…In the perovskite solar cells, TiO 2 is widely used as electron transport layers and plays a significant role in achieving high efficiency and stability of photovoltaic devices. One major reason is the conduction band of TiO 2 is lower than that of the halide perovskite such as MAPbI 3 and MASnI 3 (MA = CH 3 NH 3 , methylammonium) [16,17]. Therefore, first-principles computational studies of TiO 2 /perovskite interfaces have been an emerging topic recently [16][17][18][19][20][21][22][23][24].…”

Section: Tio 2 /Perovskite Interfacementioning

confidence: 99%

“…To do so, increasing efforts are being made to synthesize TiO 2 -based materials heterostructures and/or composites that utilize the interfacial charge transfer mechanism to promote the separation rate of electron-hole pairs [11][12][13][14][15]. A high charge separation rate is beneficial not only for photocatalysts, but also for photovoltaic cells in which TiO 2 is often used as electron transport layers as they both use the separated electrons and holes [16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Review of First-Principles Studies of TiO2: Nanocluster, Bulk, and Material Interface

2020

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TiO2 has extensive applications in the fields of renewable energy and environmental protections such as being used as photocatalysts or electron transport layers in solar cells. To achieve highly efficient photocatalytic and photovoltaic applications, ongoing efforts are being devoted to developing novel TiO2-based material structures or compositions, in which a first-principles computational approach is playing an increasing role. In this review article, we discuss recent computational and theoretical studies of structural, energetic, electronic, and optical properties of TiO2-based nanocluster, bulk, and material interface for photocatalytic and photovoltaic applications. We conclude the review with a discussion of future research directions in the field.

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“…The electron transport material (HTM) is an important part of the PSC. The proper energy level for electron injection, strong electron mobility, chemical stability, low synthesis cost, and environmental friendliness make TiO 2 an attractive candidate material [26][27][28][29]. The band gap of TiO 2 material is appropriate for reducing the transmission of holes [30].…”

Section: Introductionmentioning

confidence: 99%

Impact of HTM on lead-free perovskite solar cell with high efficiency

Das

Mandal

2022

Opt Quant Electron

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The Scaps-1d simulator was used to simulate a lead-free perovskite CH 3 NH 3 SnI 3 based solar cell devices fabricated from different hole transport materials (HTM). This research looks at two organic and two inorganic HTM layers. The cell structure used in this study is FTO/TiO 2 / CH 3 NH 3 SnI 3 /HTM(variable)/Au(variable). Spiro-OMeTAD, PEDOT:PSS, CuO and Cu 2 O are the HTM materials used. The results show that utilizing CuO as an HTM produces better outcomes than other HTMs, with an e ciency of 28.45%. The thickness, acceptor concentration (N A ), and defect density (N t ) of the perovskite layer on optoelectronic properties of the solar cell are focus of simulation studies. According to this study, an perovskite layer thickness of 1000 nm is suitable for a decent photovoltaic cell. Furthermore, by adjusting the HTM thickness and the defect density of HTM and absorber layer, promising ndings of J sc of 34.38 mAcm − 2 , V oc of 1.011 V, FF of 80.85% and PCE of 28.10% were obtained for Spiro-OMeTAD based PSC. Finally, in order to improve the device's performance, an anode material with high work function is required. Our ndings reveal that using a thin absorber layer results in low photo generated charge carriers due to less absorption, but high carrier extraction. Although more carriers are created in the cell due to increased absorption, decreased collection e ciency is related to recombination, which decreases V oc for thick perovskite layers. Device e ciency is improved by increasing the doping density up to 10 18 cm − 3 in the perovskite layer due to built-in electric eld across the solar cell. Again a very thin or thick HTL is not ideal for high PCE. For low recombination and a high ll factor, an HTM (Spiro-OMeTAD) of 1-100 nm is necessary. The great power conversion e ciency of organic HTM based lead-free PSC brings up the new possibilities for obtaining renewable energy.

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Effects of Transition Metal Substituents on Interfacial and Electronic Structure of CH3NH3PbI3/TiO2 Interface: A First-Principles Comparative Study

Cited by 18 publications

References 69 publications

Spectral Signatures of Positive and Negative Polarons in Lead-Halide Perovskite Nanocrystals

Spectral Signatures of Positive and Negative Polarons in Lead-Halide Perovskite Nanocrystals

Review of First-Principles Studies of TiO2: Nanocluster, Bulk, and Material Interface

Impact of HTM on lead-free perovskite solar cell with high efficiency

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