Using Mechanical Stress to Investigate Rashba Effect in Organic

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Using Mechanical Stress to Investigate Rashba Effect in Organic-Inorganic Hybrid Perovskites Haomiao Yu, Qi Zhang, Yaru Zhang, Kai Lu, Changfeng Han, Yijun Yang, Kai Wang, Xi Wang, Miaosheng Wang, Jia Zhang, and Bin Hu J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.9b01985 • Publication Date (Web): 28 Aug 2019 Downloaded from pubs.acs.org on August 28, 2019

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The Journal of Physical Chemistry Letters

Using Mechanical Stress to Investigate Rashba Effect in Organic-Inorganic Hybrid Perovskites Haomiao Yu†, Qi Zhang†, Yaru Zhang†, Kai Lu‡, Changfeng Han†, Yijun Yang†, Kai Wang†, Xi Wang†, Miaosheng Wang§, Jia Zhang§, and Bin Hu†,§,*

†Key

Laboratory of Luminescence and Optical Information, Ministry of Education,

School of Science, Beijing Jiaotong University

‡Wu

Han National Laboratory for Optoelectronics, Huazhong University of Science and

Technology

§Department

of Materials Science and Engineering, University of Tennessee, Knoxville,

Tennessee 37996, USA

ACS Paragon Plus Environment

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ABSTRACT

Organic-inorganic hybrid perovskites simultaneously possess strong spin-orbit coupling (SOC) and structure inversion asymmetry, establishing Rashba effect to influence light emission and photovoltaics. Here, we use mechanical bending as a convenient approach to investigate the Rashba effect through SOC in perovskite (MAPbI3-xClx) films by elastically deforming grains. It is observed that applying a concave bending can broaden the line-shape of magneto-photocurrent, increasing the internal magnetic parameter B0 from 121 to 205 mT, which indicates the SOC increasement. Interestingly, the PL lifetime is found to be enlarged from 9.9 to 14.8 ns under this bending which suggests that introducing compressive strain can essentially increase the Rashba effect through SOC, leading to an increasement on indirect band transition. Furthermore, the PL peak associated with Rashba effect is shifted from 776 to 780 nm under this mechanical bending. Therefore, mechanical bending provides a convenient experimental method to approach Rashba effect in hybrid perovskites.


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KEYWORDS: Rashba effect, perovskites, spin-orbit coupling, mechanical bending, lattice strain

TOC image


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Organic-inorganic hybrid perovskites have demonstrated attractive photovoltaic, lightemitting, lasing, and magneto-optical properties, leading to interesting multifunctional semiconducting materials1–7. Of these attractive properties, the unique characteristics rely on Rashba effect caused by spin-orbit coupling (SOC) under structural inversion asymmetry8–17. Essentially, Rashba effect can be realized in structural inversion asymmetry when the spin-up and spin-down energies become non-degenerate in momentum space under the influence of SOC. Within the framework of Rashba effect, an optical absorption is fully allowed due to spin selection rule, yielding strong absorption coefficients. However, upon optical absorption, an excited electron can flip its spin due to SOC and transition to opposite spin-band structure with spin-forbidden recombination, leading to an enlarged lifetime. As a result, strong optical absorption and long carrier lifetime can concurrently occur12, providing a precondition to generate remarkable photovoltaics. On the other hand, electron-phonon coupling provides a mechanism of breaking the spin-forbidden recombination, activating downward electronic transition towards light emission17– 19.

Therefore, Rashba effect plays an important role in developing photovoltaic and light-emitting

actions in organic-inorganic hybrid perovskites. In this work, we mechanically deform the hybrid perovskite (MAPbI3-xClx) film coated on flexible PET substrate to morphologically vary the SOC by introducing a vertically compressive stress through applying a concave bending. At the same time, we use photoluminescence (PL) spectra to approach Rashba effect. The structural deformation was characterized by X-ray diffraction (XRD) measurements under compressive bending. The SOC was monitored by magneto-photocurrent and polarization-dependent photocurrent. Our studies show that applying a vertically compressive stress can mainly increase the Rashba effect by introducing grain deformation and enhancing intrinsic SOC. Consequently,


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the photoexcited states recombine through electron-phonon coupling mechanism with an enlarged lifetime in organic-inorganic hybrid perovskites. Here we applied mechanical bending onto flexible perovskite device to introduce grain deformation on perovskite film. The flexible substrate is bent with concave shape as illustrated in Figure 1a. This concave bending generates two different effects: tensile stress laterally and c

1.5 1.0

bending

0.5 0.0

flat

Intensity (a.u.)

b

Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


11 12 13 14 15 16 17 2 degree

1.5 1.0 0.5

bending flat

0.0 30 31 32 33 34 35 36 37 2 degree

Figure 1. The XRD spectra of flexible perovskite film at flat and bending condition. (a) A concave bending diagram. (b) (110) plane and (c) (310)﹠(132) plane.

compressive stress vertically. As a result, the observed bending effects result from the combination of laterally tensile stress and vertically compressive stress. To examine bending induced deformation in perovskite film, out-of-plane XRD measurement on the sample of PET/MAPbI3xClx

were performed. To make a clear comparison, we present the (110), (310) and (132) plane of

perovskite film with/without mechanical bending, the complete XRD spectra can be found in Supporting Information (Figure S1). As we can see in Figure 1b, the XRD peak corresponding to (110) plane of MAPbI3-xClx shifts from 14.16° to 14.24° with mechanical bending. Similarly, as shown in Figure 1c, the XRD peak corresponding to (310) plane shifts from 31.94° to 32.02° and the (132) plane shifts from 35.04° to 35.12° under this mechanical bending. This provides an evidence that such mechanical bending generates a lattice strain in the perovskite (MAPbI3-xClx) film. Especially, shifting to higher angle means that compressive strain dominates the bending


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effects in our flexible perovskite devices. Noticing that hybrid perovskites possess structure dependent SOC20–22, the lattice strain generated by mechanical stress may influence Rashba effect through SOC. To explore the effects of mechanical bending on SOC, flexible perovskite solar cells with the structure of PET/ITO/PEDOT:PSS/MAPbI3-xClx/PCBM/PEI/Ag were fabricated to investigate the magneto-photocurrent (magneto-Jsc) and polarization-dependent photocurrent properties. The JV characteristics of the flexible device under one sun condition are presented in Figure S2. The flexible perovskite solar cell shows a power conversion efficiency (PCE) of 12.97 % with Jsc of 17.47 mA/cm2, Voc of 1.00 V and FF of 0.74. In organic-inorganic hybrid perovskites, the strong spin-orbit coupling leads to three non-degenerate states, J = 3/2, J =1/2 and S = 1/223,24. Here, the orbit motion and spin of carriers are strongly coupled, the total angular momentum J = L + S must be considered. Thus, the spin states of both the valence band maximum (VBM) and the conduction band minimum (CBM) can be given by |𝐽,𝑚𝐽⟩, where J is the angular momentum quantum number and mJ is the magnetic quantum number. Taking into strong SOC in the perovskites, when the electron and hole states are combined, they form dark state of J = 0: |0,0⟩ =

1 ( 2 |↓↓⟩𝑒|↑⟩ℎ

― |↑↑⟩𝑒|↓⟩ℎ)

(1)

and three-fold degenerate bright states of J = 1: (2)

|1, ― 1⟩ = |↓↓⟩𝑒|↓⟩ℎ |1,0⟩ =

1 ( 2 |↓↓⟩𝑒|↑⟩ℎ

|1, + 1⟩ = |↑↑⟩𝑒|↑⟩ℎ

+ |↑↑⟩𝑒|↓⟩ℎ)

(3) (4)

The dark (J = 0) and bright (J = 1) states are non-radiative and radiative states, respectively25,26. Magneto-Jsc refers to the phenomenon that an external magnetic field can change the photocurrent in solar cells. It can be observed by satisfying two conditions: (i) a magnetic field changes the


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populations on dark states and bright states under photoexcitation and (ii) dark states and bright states generate different photocurrents due to their different dissociation rates27–29. Before applying an external magnetic field, the populations on different excitonic states reach an equilibrium based on the competition between the spin conservation from exchange interaction and the spin mixing from SOC. After applying an external magnetic field, the equilibrium can be broken by competing with SOC, changing the populations between different excitonic states28. Obviously, increasing the populations of bright states by magnetic field can decrease Jsc, leading to a negative magnetic field effect (MFE). On the contrast, increasing the populations of dark states will lead to a positive MFE, as illustrated in Figure 2a. Figure 2b shows the magneto-Jsc curve of flexible

b

Normalized Jsc change

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0.0 -0.2

flat B0 = 121 mT

-0.4

bending B0 = 205 mT

-0.6 -0.8 -1.0 0

200 400 600 800 1000 Magnet field (mT)

Figure 2. Magneto-photocurrent measurements. (a) Diagram to schematically show magnetic field


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dependent photocurrent. (b) Magneto-Jsc curve of flexible perovskite solar cell with/without bending.

PET/ITO/PEDOT:PSS/MAPbI3-xClx/PCBM/PEI/Ag device with/without mechanical bending. It can be seen that the device with/without bending both exhibit negative MFE, meaning that an external magnetic field breaks the equilibrium of intersystem crossing and enhances the population of bright states, leading to a reduction in photocurrent. More importantly, flat and bent devices show narrower and broader line-shapes in magneto-Jsc curves, respectively. The line-shape can be defined as the changing rate on the dark-state/bright-state ratio by external magnetic field, it can reflect the strength of SOC. When a SOC effect exists, an external magnetic field becomes more difficult to disturb intersystem crossing between dark and bright states, resulting in a broader line-shape in magneto-Jsc. On the other hand, when the SOC is weak, an external magnetic field is much easier to change the dark-state/bright-state ratio, leading to a narrower line-shape in magneto-Jsc. Hence, the broader line-shape of bent device indicates that SOC effect increases upon introducing mechanical stress onto perovskite film. By using the curve fitting based on the Lorentzian equation

∆𝐽𝑠𝑐(𝐵) 𝐽𝑠𝑐(0)

𝑩2

∝ 𝑩𝟐 + 𝑩𝟐, where B0 represents the internal magnetic parameter which is 𝟎

related to SOC effect, we can determine B0 = 121 mT and B0 = 205 mT for flat and bent device, respectively. Clearly, the internal magnetic parameter B0 is largely increased upon device bending, indicating that bending indeed increases SOC in hybrid perovskites. To further confirm this mechanical bending effect on SOC, we also performed polarizationdependent photocurrent studies. Our experimental method is established by switching the photoexcitation between linear and circular polarizations at the same intensity to detect the photocurrent difference Jsc. The experimental setup can be found in Figure S3. The principle of this method is illustrated in Figure 3a. By transferring incident circular polarization momentum to


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orbit momentum, left-hand ( +) and right-hand ( -) circular photoexcitations generate bright states of |1, + 1⟩ and |1, ― 1⟩ with different magnetic dipole moments, respectively. Therefore, a

b Jsc (mA/cm2)

-0.07

Jsc (mA/cm2)

0

10

20

30

40

50

60

r=40mm

Jsc=0%

r=48mm

Jsc=1.8%

flat

Jsc=3.3%

-0.08 -0.09 -0.10 -0.11 -0.62

-0.64

-0.66

Jsc (mA/cm2)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


-1.90 -1.95

linearly excitation

-2.00 -2.05

0

10

circularly excitation linearly

circularly excitation

excitation

20

30

40

50

60

Time (s)

Figure 3. Polarization-dependent photocurrent studies. (a) Principle of circular and linear excitation

experiments.

(b)

The

Jsc

of

flexible

perovskite

solar

cell

(PET/ITO/PEDOT:PSS/MAPbI3-xClx/PCBM/PEI/Ag) with different bending curvature radii excited by linearly and circularly polarized light with identical intensity (17.8 mW/cm2) and same wavelength (532 nm).

left-hand circular light generates the bright states with |1, + 1⟩ with the same-directional orbital momentum, providing stronger total orbital momentum to change photo-generated J = 1 bright states to J = 0 dark states. On contrary, a linearly polarized light, equivalently to the combination of left-hand ( +) and right-hand ( -) circularly polarized lights, generates both |1, + 1⟩ and


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|1, ― 1⟩ with opposite-directional orbital momentums, resulting in low total orbital momentum to change bright states to dark states. Because dark states are more difficult to recombine as compared to bright states according to spin selection rule, circularly and linearly polarized lights with same intensity lead to higher and lower Jsc, resulting in a Jsc. Thus, Jsc reflects an optically induced spin mixing by changing the SOC due to orbit-orbit interaction by changing the light excitation from linear to circular polarization. On the other hand, intrinsic SOC can initiate spin mixing between dark and bright states, which decreases Jsc measured by switching the photoexcitation between linear and circular polarizations. Therefore, there exists a competition between opticallyoperated and intrinsic SOC-operated intersystem crossing. This means Jsc generated by circularly and linearly photoexcitation can reflect the strength of SOC, a smaller Jsc corresponds to a stronger SOC while a larger Jsc is corresponding to a weaker SOC. Therefore, monitoring the Jsc magnitude during switching the photoexcitation between linear and circular polarizations can provide the information of SOC in the perovskites upon mechanical bending. As shown in Figure 3b, flat PSC device exhibits a stair-stepping Jsc upon switching photoexcitation between linearly and circularly lights. More importantly, a mechanical bending (r = 48 mm) decreases the the Jsc amplitude from 3.3 % to 1.8 %. Further increasing the bending curvature to 40 mm leads to a negligible Jsc. Clearly, the decreased Jsc gives direct evidence that SOC is increased in the hybrid perovskite film by mechanical bending. This suggests that mechanical bending can induce the strain and consequently increase the SOC in the perovskite film. To exclude any effect from transport layers in the flexible perovskite solar cells, we also performed the polarization-dependent photoluminescence (PL) measurements on MAPbI3-xClx film (Figure S4). The PL intensity difference (∆PL) measured by switching the photoexcitation between linear and circular polarizations can reflect the SOC strength, similar to Jsc measurements. As shown in Figure S4,


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the ∆PL decreases from 2.8 % to nearly zero with mechanical bending onto the perovskite film, indicating that the SOC enhancement by this mechanical stress originates from the perovskite film. In principle, increasing SOC can enhance Rashba effect. To evaluate the Rashba effect upon mechanical bending, time-resolved photoluminescence spectroscopy (TRPL) is performed on flexible perovskite film (PET/MAPbI3-xClx). As shown in Figure 4a, the bended MAPbI3-xClx film

b

1.0

Normalized SSPL

a

Normalized Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0.8 0.6 0.4

flat bending

0.2 0.0

0

20

40 60 Time (ns)

80

1.0 0.8 0.6 0.4 0.2 0.0 650

flat bending

700 750 800 850 Wavelength (nm)

Figure 4. PL spectra to evaluate Rashba effects. (a) Normalized PL lifetime and (b) steady state PL (SSPL) of MAPbI3-xClx perovskite film with/without mechanical bending. The SSPL spectrum is composed of two distinct peaks, black and red dashes are the two fitted curves of SSPL under flat condition and with mechanical bending, respectively.

exhibits a longer PL lifetime (14.8 ns) than flat film (9.9 ns), suggesting that this mechanically introduced structural deformation increases the Rashba effect in the hybrid perovskites. Furthermore, we fitted the steady-state photoluminescence (SSPL) of the perovskite film with/without mechanical bending by two distinct peaks since one peak is insufficient to fit the SSPL curves. As shown in Figure 4b, under flat condition, the SSPL spectrum is composed of a main peak located at 755 nm and a shoulder located at 776 nm. With mechanical bending, the main peak stays unchanged while the shoulder red-shifts to 780 nm. It has been indicated that the shoulder is from an indirect transition below the direct bandgap30. Here, by using the separation


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between main peak and shoulder peak, we can obtain the Rashba splitting energy of 45 meV without mechanical bending, which increases to 53 meV with mechanical bending, further confirming the increased Rashba effect by introducing mechanical stress. Essentially, this leads to a longer PL lifetime upon mechanical bending, as experimentally indicated in Figure 4a. In summary, Rashba effect is approached by mechanical bending in hybrid MAPbI3-xClx perovskites. The XRD spectra indicate that a concave bending onto flexible perovskite film leads to compressive lattice strain. Such grain deformation enhances SOC according to magnetophotocurrent and polarization-dependent photocurrent studies. By using PL spectra to evaluate the Rashba effect, we find that this mechanically introduced structural deformation can essentially increase the Rashba effect in the hybrid perovskites by enhancing SOC. With increasing Rashba effect, the photoexcited states can relax through electron-phonon coupling mechanism with an enlarged lifetime upon applying mechanical stress.

ASSOCIATED CONTENT

Supporting Information.

Experimental section and Figures S1−S4.

AUTHOR INFORMATION

Corresponding Authors


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*E-mail: [email protected]

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (Grant No. 61634001, U1601651, 61475051 and 61604010) and the Fundamental Research Funds for the Central Universities (2019RC019, 2017JBZ105). The authors at University of Tennessee acknowledge the support from National Science Foundation (NSF-1911659).

REFERENCES (1)

Yang, W. S.; Park, B.-W.; Jung, E. H.; Jeon, N. J.; Kim, Y. C.; Lee, D. U.; Shin, S. S.; Seo, J.; Kim, E. K.; Noh, J. H.; et al. Iodide Management in Formamidinium-LeadHalide–Based Perovskite Layers for Efficient Solar Cells. Science. 2017, 356, 1376–1379.

(2)

Green, M. A.; Ho-Baillie, A. Perovskite Solar Cells: The Birth of a New Era in Photovoltaics. ACS Energy Lett. 2017, 2, 822–830.

(3)

Seok, S. Il; Grätzel, M.; Park, N.-G. Methodologies toward Highly Efficient Perovskite Solar Cells. Small 2018, 14, 1704177.


13


(4)

Page 14 of 17

Tan, Z.-K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.; Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D.; et al. Bright Light-Emitting Diodes Based on Organometal Halide Perovskite. Nat. Nanotechnol. 2014, 9, 687–692.

(5)

Zhang, H.; Lin, H.; Liang, C.; Liu, H.; Liang, J.; Zhao, Y.; Zhang, W.; Sun, M.; Xiao, W.; Li, H.; et al. Organic-Inorganic Perovskite Light-Emitting Electrochemical Cells with a Large Capacitance. Adv. Funct. Mater. 2015, 25, 7226-7232.

(6)

Chin, X. Y.; Cortecchia, D.; Yin, J.; Bruno, A.; Soci, C. Lead Iodide Perovskite LightEmitting Field-Effect Transistor. Nat. Commun. 2015, 6, 7383.

(7)

Xing, G.; Mathews, N.; Lim, S. S.; Yantara, N.; Liu, X.; Sabba, D.; Grätzel, M.; Mhaisalkar, S.; Sum, T. C. Low-Temperature Solution-Processed Wavelength-Tunable Perovskites for Lasing. Nat. Mater. 2014, 13, 476–480.

(8)

Isarov, M.; Tan, L. Z.; Bodnarchuk, M. I.; Kovalenko, M. V.; Rappe, A. M.; Lifshitz, E. Rashba Effect in a Single Colloidal CsPbBr3 Perovskite Nanocrystal Detected by Magneto-Optical Measurements. Nano Lett. 2017, 17, 5020–5026.

(9)

Li, M.; Li, L.; Mukherjee, R.; Wang, K.; Liu, Q.; Zou, Q.; Xu, H.; Tisdale, J.; Gai, Z.; Ivanov, I. N.; et al. Magnetodielectric Response from Spin-Orbital Interaction Occurring at Interface of Ferromagnetic Co and Organometal Halide Perovskite Layers via Rashba Effect. Adv. Mater. 2017, 29, 1603667.

(10)

Kepenekian, M.; Robles, R.; Katan, C.; Sapori, D.; Pedesseau, L.; Even, J. Rashba and Dresselhaus Effects in Hybrid Organic-Inorganic Perovskites: From Basics to Devices. ACS Nano 2015, 9, 11557–11567.


14

Page 15 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(11)

Kepenekian, M.; Even, J. Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics. J. Phys. Chem. Lett. 2017, 8, 3362–3370.

(12)

Yu, Z.-G. The Rashba Effect and Indirect Electron–Hole Recombination in Hybrid Organic–Inorganic Perovskites. Phys. Chem. Chem. Phys. 2017, 19 (23), 14907–14912.

(13)

Etienne, T.; Mosconi, E.; De Angelis, F. Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells? J. Phys. Chem. Lett. 2016, 7, 1638–1645.

(14)

Niesner, D.; Wilhelm, M.; Levchuk, I.; Osvet, A.; Shrestha, S.; Batentschuk, M.; Brabec, C.; Fauster, T. Giant Rashba Splitting in CH3NH3PbBr Organic-Inorganic Perovskite. Phys. Rev. Lett. 2016, 117, 126401.

(15)

Zhai, Y.; Baniya, S.; Zhang, C.; Li, J.; Haney, P.; Sheng, C.-X.; Ehrenfreund, E.; Vardeny, Z. V. Giant Rashba Splitting in 2D Organic-Inorganic Halide Perovskites Measured by Transient Spectroscopies. Sci. Adv. 2017, 3, e1700704.

(16)

Hu, S.; Gao, H.; Qi, Y.; Tao, Y.; Li, Y.; Reimers, J. R.; Bokdam, M.; Franchini, C.; Di Sante, D.; Stroppa, A.; et al. Dipole Order in Halide Perovskites: Polarization and Rashba Band Splittings. J. Phys. Chem. C 2017, 121, 23045–23054.

(17)

Zheng, F.; Tan, L. Z.; Liu, S.; Rappe, A. M. Rashba Spin-Orbit Coupling Enhanced Carrier Lifetime in CH3NH3PbI3. Nano Lett. 2015, 15, 7794–7800.

(18)

Kawai, H.; Giorgi, G.; Marini, A.; Yamashita, K. The Mechanism of Slow Hot-Hole Cooling in Lead-Iodide Perovskite: First-Principles Calculation on Carrier Lifetime from Electron-Phonon Interaction. Nano Lett. 2015, 15, 3103–3108.


15


(19)

Page 16 of 17

Long, R.; Liu, J.; Prezhdo, O. V. Unravelling the Effects of Grain Boundary and Chemical Doping on Electron–Hole Recombination in CH3NH3PbI3 Perovskite by Time-Domain Atomistic Simulation. J. Am. Chem. Soc. 2016, 138, 3884–3890.

(20)

Amat, A.; Mosconi, E.; Ronca, E.; Quarti, C.; Umari, P.; Nazeeruddin, M. K.; Grätzel, M.; De Angelis, F. Cation-Induced Band-Gap Tuning in Organohalide Perovskites: Interplay of Spin–Orbit Coupling and Octahedra Tilting. Nano Lett. 2014, 14, 3608–3616.

(21)

Quarti, C.; Mosconi, E.; De Angelis, F. Interplay of Orientational Order and Electronic Structure in Methylammonium Lead Iodide: Implications for Solar Cell Operation. Chem. Mater. 2014, 26, 6557–6569.

(22)

Im, J.; Stoumpos, C. C.; Jin, H.; Freeman, A. J.; Kanatzidis, M. G. Antagonism between Spin-Orbit Coupling and Steric Effects Causes Anomalous Band Gap Evolution in the Perovskite Photovoltaic Materials CH3NH3Sn1-xPbxI3. J. Phys. Chem. Lett. 2015, 6, 3503– 3509.

(23)

Even, J.; Pedesseau, L.; Jancu, J. M.; Katan, C. Importance of Spin-Orbit Coupling in Hybrid Organic/Inorganic Perovskites for Photovoltaic Applications. J. Phys. Chem. Lett. 2013, 4, 2999–3005.

(24)

Kim, M.; Im, J.; Freeman, A. J.; Ihm, J.; Jin, H. Switchable S = 1/2 and J = 1/2 Rashba Bands in Ferroelectric Halide Perovskites. Proc. Natl. Acad. Sci. 2014, 111, 6900–6904.

(25)

Yu, Z. G. Effective-Mass Model and Magneto-Optical Properties in Hybrid Perovskites. Sci. Rep. 2016, 6, 28576.

(26)

Becker, M. A.; Vaxenburg, R.; Nedelcu, G.; Sercel, P. C.; Shabaev, A.; Mehl, M. J.; Michopoulos, J. G.; Lambrakos, S. G.; Bernstein, N.; Lyons, J. L.; et al. Bright Triplet Excitons in Caesium Lead Halide Perovskites. Nature 2018, 553, 189–193.


16

Page 17 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(27)

Zhang, J.; Wu, T.; Duan, J.; Ahmadi, M.; Jiang, F.; Zhou, Y.; Hu, B. Exploring SpinOrbital Coupling Effects on Photovoltaic Actions in Sn and Pb Based Perovskite Solar Cells. Nano Energy 2017, 38, 297–303.

(28)

Hsiao, Y.-C.; Wu, T.; Li, M.; Hu, B. Magneto-Optical Studies on Spin-Dependent Charge Recombination and Dissociation in Perovskite Solar Cells. Adv. Mater. 2015, 27, 2899– 2906.

(29)

Wu, T.; Hsiao, Y.-C.; Li, M.; Kang, N.-G.; Mays, J. W.; Hu, B. Dynamic Coupling between Electrode Interface and Donor/Acceptor Interface via Charge Dissociation in Organic Solar Cells at Device-Operating Condition. J. Phys. Chem. C 2015, 119, 2727−2732.

(30)

Wang, T.; Daiber, B.; Frost, J. M.; Mann, S. A.; Garnett, E. C.; Walsh, A.; Ehrler, B. Indirect to Direct Bandgap Transition in Methylammonium Lead Halide Perovskite. Energy Environ. Sci. 2017, 10, 509–515.


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Using Mechanical Stress to Investigate Rashba Effect in Organic

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