Tailoring the energy landscape in quasi-2d halide. perovskites enables efficient green light emission

Transcription

1 Supporting Information Tailoring the energy landscape in quasi-2d halide perovskites enables efficient green light emission Li Na Quan, 1,2 Yongbiao Zhao, 3 F. Pelayo García de Arquer, 1 Randy Sabatini, 1 Grant Walters, 1 Oleksandr Voznyy, 1 Riccardo Comin, 1 Yiying Li, 3 James Z. Fan, 1 Hairen Tan 1, Jun Pan, 4 Mingjian Yuan, 1 Osman M. Bakr, 4 Zhenghong Lu, 3 * Dong Ha Kim, 2 * Edward H. Sargent 1 * 1 Department of Electrical and Computer Engineering, University of Toronto, 10 King s College Road, Toronto, Ontario, M5S 3G4, Canada. 2 Department of Chemistry and Nano Science, Ewha Woman s University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea. 3 Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada. 4 Division of Materials Science and Engineering, King Abdullah University of Science and Technology, Thuwal , Kingdom of Saudi Arabia These authors contributed equally to this work. ted.sargent@utoronto.ca; dhkim@ewha.ac.kr; zhenghong.lu@utoronto.ca

2 Stochastic Monte Carlo modelling of recombination kinetics. The photoemission, recombination, and photocharge transfer dynamics were simulated based on eq. 1 with a stochastic Monte Carlo algorithm. Briefly it consisted of: 1. Discretization of the perovskite domain Based on the average grain size obtained from atomic-force-microscopy measurements, we discretized the photoactive perovskite in 10 x 10 x 10 nm 3 plaques. Typically, a surface of 200 nm x 200 nm was simulated. 2. Distribution of the different domains Once the perovskite support was tessellated, every grain was associated to a given perovskite dimension following a uniform random assignation based on the weighted contribution of the different n i. 3. Excitation Photon absorption takes place during a time interval of 150 fs (following the dynamics of the pump used in transient absorption experiments). Pump power was then converted to number of photons, and these absorbed in the individual unit cells. Absorption probability was calculated based on the volume the unit cells and the absorption coefficient of the perovskite. 4. Run A time step of dt = 250 fs was considered by default. At every time step a number is randomly generated (p) and the perovskite is screened. For each of the photoexcited entities (N exc ) present in a unit cell, the next algorithm, based on the binomial approximation of the potentially occurring events, is used: - If dt A trap > p then decrease N exc (trap assisted non-radiative recombination) - If dt N exc B rad > p then decrease N exc and release a photon (radiative recombination) - If dt N exc 2 C Auger > p and N exc > 2, decrease N exc (Auger assisted, non-radiative recombination) - If dt k transfer > p move the most likely acceptor. This is calculated based on the minimum Eucledian distance to the allowed, narrower bandgap, acceptors (energy transfer). Where A trap, B rad, C Auger and k transfer are the input elemental rates of the associated processes.

3 S1. Unit cell structure of quasi 2D and 3D perovskites. Figure S1. Unit cell structure of MAPbBr 3 and quasi-2d perovskites with <n>=3 and <n>=5, showing the evolution of dimensionality from quasi-2d (n=3) to 3D (n= ).

4 S2. XRD spectra of quasi-2d and 3D perovskites. Figure S2. Film XRD spectra for <n>=3 (engineered energy landscape) and <n>=5 (graded landscape) perovskites and MAPbBr 3 perovskite.

5 S3. AFM maps of quasi-2d and 3D perovskites. Figure S3. AFM image of <n>=3 (engineered energy landscape), <n>=5 (graded landscape) perovskites (a-d) and MAPbBr 3 perovskites (e-f). The average grain size for <n>=3 and <n>=5 is of ~10 nm, whereas for the 3 D samples an average domain size of ~100 nm is obtained.

6 S4. AFM maps of flat energy landscape quasi-2d and engineered quasi-2d perovskites. Figure S4. AFM image of <n>=3 perovskite films with toluene (flat energy landscape) (a) and chloroform (engineered energy landscape) (b) as the antisolvent.

7 S5. Absorption and photoluminescence (PL) spectra of engineered energy landscape quasi-2d and 3D perovskites. Figure S5. Absorption and PL spectra of (a) <n>=3 (engineered energy landscape), (b) <n>=5 (graded landscape) quasi-2d and (c) MAPbBr 3 3D perovskites, respectively.

8 S6. UPS spectra of quasi-2d and 3D perovskites. Figure S6. UPS spectra of <n>=3 (engineered energy landscape) and <n>=5 (graded landscape), MAPbBr 3, perovskites. The resulting energy bands position is shown in Figure 4 (main manuscript).

9 S7. Transient absorption study of 2D and 3D perovskites. Figure S7. Time-wavelength dependent TA color map for 2D PEA 2 PbBr 4 perovskite (a), 3D MAPbBr 3 perovskite (b), time dependent transient absorption traces of PEA 2 PbBr 4 (c) and MAPbBr 3 (d) perovskites.

10 S8. Transient absorption study of <n>=5 quasi-2d perovskites. Figure S8. Photoluminescence spectra of <n>=5 quasi-2d perovskite made with toluene as an anti-solvent (flat energy landscape) (a-b) and that of energy landscape engineered quasi-2d perovskite (made with chloroform as an anti-solvent) (c-d).

11 S9. Transient PL study of engineered energy landscape quasi-2d perovskites. Figure S9. a-c) Time-resolved 2D-PL results of quasi-2d <n>=3 (engineered energy landscape) perovskite.

12 S10. Recombination and funneling dynamics for <n> = 3 and <n>=5. Figure S10. Recombination and funneling dynamics of <n> = 3 (engineered energy landscape) (a-b) <n> = 5 (graded energy landscape) (c-d) perovskites. (a) Photocharges as a function of time in the different <n> = 3 domains and the instantaneous recombination yield (b). (c) Photocharges as a function of time in the different <n> = 5 domains and the instantaneous recombination yield.

13 S11. LED current efficiency-voltage characteristics.. Figure S11. Current efficiency-voltage curve of LED device with MAPbBr 3, <n>=3 and <n>=5 perovskites.

14 Normalized EL intensity S12. EL spectra MAPbBr 3 (532nm) n=5 (526nm) n=3 (520nm) Wavelength (nm) Figure S12. EL spectra of the device with MAPbBr 3, <n>=3 and <n>=5 perovskites.

15 S13. Luminance vs EQE curve. Figure S13. Luminance versus EQE plot for each of 10 devices of the different type perovskites.

16 S14. LED stability. Figure S14. Operational stability of <n>=5 perovskite at 100cd/m 2 luminance.