Supporting Information

Transcription

1 Supporting Information Blue-Green Colour Tunable Solution Processable Organolead Chloride- Bromide Mixed Halide Perovskites for Optoelectronic Applications Aditya Sadhanala, 1* Shahab Ahmad, 2 Baodan Zhao, 1 Nadja Giesbrecht, 3 Phoebe M. Pearce, 1 Felix Deschler, 1 Robert L. Z. Hoye, 1 Karl C Gödel, 1 Thomas Bein, 3 Pablo Docampo, 3 Siân E Dutton, 1 Michael F.L. De Volder, 2 Richard H. Friend 1* 1 Cavendish Laboratory, JJ Thomson Avenue, CB3 0HE, Cambridge, United Kingdom 2 Institute for Manufacturing, Department of Engineering, Cambridge University, 17 Charles Babbage Road, CB3 0FS, Cambridge, United Kingdom 3 Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, München, Germany AUTHOR INFORMATION Corresponding Author *as2233@cam.ac.uk, rhf10@cam.ac.uk Present Addresses Photovoltaic Research Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

2 Keywords: Blue LED, perovskite solar cells, narrow FWHM, disorder, bandgap tuning Figure S1: (a) PDS absorption data for the 3:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated, showing monotonic bandgap; tuning with changing composition. They also demonstrate sharp band-edges and clean sub-bandgap. (b) Urbach energy for all the samples showing low disorder. The 24 and 45% chloride samples demonstrate the lowest Urbach energy of ~ 17 mev and the samples with no chloride content shows Urbach energy of ~19 mev and the remaining samples with chloride content higher than 45% show higher Urbach energies of ~23 mev. These Urbach energy values are much lower than those obtained for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films, which makes them more useful for solar cell applications.

3 Figure S2. (a-f) PDS spectra for the 3:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated. The grey lines in each plot are the linear fits to the Urbach tail used to calculate the Urbach energy and the obtained Urbach energy E u which is indicated for each sample.

4 Figure S3: (a) X-ray diffraction (XRD) data for the 3:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated. (b) and (c) XRD patterns showing the evolution of the (100) and the (200) reflection as a function of composition for the same samples.

5 Figure S4: Energy dispersive X-ray spectroscopy (EDX) data for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite solid solutions based thin films with different chloride-bromide ratios as indicated showing close match between the concentration in solution and that in thin films.

6 Figure S5: (a) X-ray diffraction (XRD) data for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated. (b) XRD patterns showing the evolution of the (100) reflection as a function of composition for the same samples.

7 Figure S6: UPS spectra of the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] different chloride-bromide ratios as indicated, on gold substrate. (a) UPS spectra of the top of the Valance band maxima (E V ) for the perovskite samples as a function of composition giving the difference between the fermi energy level (E F ) and E V of around 1.08 ev and 0.77 ev for 100% and 0% chloride samples respectively. (b) Photoemission cut-off for the perovskite samples as a function of composition, from which the vacuum level of the film is extracted. The E F for 100% and 0% chloride samples are -5.4 ev and -5.2 ev respectively.

8 Figure S7. (a-f) PDS spectra for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated. The grey lines in each

9 plot are the linear fits to the Urbach tail used to calculate the Urbach energy and the obtained Urbach energy E u which is indicated for each sample.

10 Figure S8. (a-f) Show the normalized PL decay for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated with the fits bi-exponential fits showing the bimolecular nature of the PL decay

11 Table S1. Enlists the calculated PL decay times from the bi-exponential fits for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloridebromide ratios as indicated

12 Normalized PL intensity CH 3 NH 3 Pb(Br 0.4 Cl 0.6 ) 3 Before white light exposure After white light exposure Wavelength (nm) Figure S9: PL spectra for the 60% chloride content sample (CH 3 NH 3 Pb(Br 0.4 Cl 0.6 ) 3 ) measured before and immediately after exposure to 1sun intensity (100 mw/cm 2 ) demonstrating no change in the PL peak position proving the photo-stability of these materials.

13 Figure S10: Plot of the natural log of the PL Vs inverse temperature for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br 0.4 Cl 0.6 ) 3 perovskite thin films showing high integrated PL at lower temperatures and high activation energies in the range of ~590 mev for this thermally-activated PL quenching process

14 Figure S11. Observed X-ray diffraction pattern (red crosses) and calculated Le Bail intensity (black line) for (a) CH 3 NH 3 PbBr 3, (b) CH 3 NH 3 Pb(Br 0.6 Cl 0.4 ) 3 and (c) CH 3 NH 3 PbCl 3 at room

15 temperature. Tick marks indicate - perovskite [as indicated] (upper) and PbX 2 (lower) [X = Br, Cl] and mixed perovskite (upper and middle) and lead acetate (lower).

16 Figure S12. SEM images of for the 3:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated.

17 Figure S13. SEM images of for the 5:1 molar starting ratio CH 3 NH 3 Pb(Br x Cl 1-x ) 3 [0 x 1] perovskite thin films with different chloride-bromide ratios as indicated.