Z for a help with photography, Professor Dr. H. Grutzmacher and Dr. G. Muller for a sample of Irgacure 819 photoinitiator, Dr. F. Krumeich for EDX measurements, Dr. M. Dobeli for RBS measurements (ETH Laboratory of Ion Beam Physics), and Dr. N. Stadie forDOI: 10.1021/nl5048779 Nano Lett. 2015, 15, 3692-Nano Letters reading the manuscript. We gratefully acknowledge the support from the Electron Microscopy Center at Empa as well as the Scientific Center for Optical and Electron Microscopy (ScopeM) at ETH Zurich.Letter(1) Talapin, D. V.; Lee, J.-S.; Kovalenko, M. V.; Shevchenko, E. V. Chem. Rev. 2009, 110, 389-458. (two) Lan, X.; Masala, S.; Sargent, E. H. Nat. Mater. 2014, 13, 233-240. (3) Hetsch, F.; Zhao, N.; Kershaw, S. V.; Rogach, A. L. Mater. Currently 2013, 16, 312-325. (four) Shirasaki, Y.; Supran, G. J.; Bawendi, M. G.; Bulovic, V. Nat. Photonics 2013, 7, 13-23. (5) Chen, O.; Zhao, J.; Chauhan, V. P.; Cui, J.; Wong, C.; Harris, D. K.; Wei, H.; Han, H.-S.; Fukumura, D.; Jain, R. K.; Bawendi, M. G. Nat. Mater. 2013, 12, 445-451. (6) Murray, C. B.; Norris, D. J.; Bawendi, M. G. J. Am. Chem. Soc. 1993, 115, 8706-8715. (7) Aldakov, D.; Lefrancois, A.; Reiss, P. J. Mater. Chem. C 2013, 1, 3756-3776. (eight) Fan, F.-J.; Wu, L.; Yu, S.-H. Power Environ. Sci. 2014, 7, 190- 208. (9) Yu, X.; Shavel, A.; An, X.; Luo, Z.; Ibanez, M.; Cabot, A. J. Am. Chem. Soc. 2014, 136, 9236-9239. (10) Gratzel, M. Nat. Mater. 2014, 13, 838-842. (11) Green, M. A.; Ho-Baillie, A.; Snaith, H. J. Nat. Photonics 2014, 8, 506-514. (12) Park, N.-G. J. Phys. Chem. Lett. 2013, four, 2423-2429. (13) Zhou, H.; Chen, Q.; Li, G.; Luo, S.; Song, T.-b.; Duan, H.-S.; Hong, Z.; You, J.; Liu, Y.; Yang, Y. Science 2014, 345, 542-546. (14) Chung, I.; Lee, B.; He, J.; Chang, R. P. H.; Kanatzidis, M. G. Nature 2012, 485, 486-489. (15) Moller, C. K. Nature 1958, 182, 1436-1436. (16) Sharma, S.; Weiden, N.; Weiss, A. Z. Phys. Chem. 1992, 175, 63-80. (17) Trots, D. M.; Myagkota, S. V. J. Phys. Chem. Solids 2008, 69, 2520-2526. (18) Stoumpos, C. C.; Malliakas, C. D.; Kanatzidis, M. G. Inorg. Chem. 2013, 52, 9019-9038. (19) Babin, V.; Fabeni, P.; Nikl, M.; Nitsch, K.; Pazzi, G. P.; Zazubovich, S. Phys. Status Solidi B 2001, 226, 419-428. (20) Christodoulou, S.; Vaccaro, G.; Pinchetti, V.; De Donato, F.; Grim, J. Q.; Casu, A.; Genovese, A.; Vicidomini, G.Methoxsalen ; Diaspro, A.; Brovelli, S.; Manna, L.; Moreels, I. J. Mater. Chem. C 2014, two, 3439- 3447. (21) Wehrenfennig, C.; Liu, M.; Snaith, H. J.; Johnston, M. B.; Herz, L. M. J. Phys.Antiflammin 2 Chem.PMID:23996047 Lett. 2014, 5, 1300-1306. (22) Zhang, M.; Yu, H.; Lyu, M.; Wang, Q.; Yun, J.-H.; Wang, L. Chem. Commun. 2014, 50, 11727-11730. (23) Xing, G.; Mathews, N.; Lim, S. S.; Yantara, N.; Liu, X.; Sabba, D.; Gratzel, M.; Mhaisalkar, S.; Sum, T. C. Nat. Mater. 2014, 13, 476- 480. (24) Deschler, F.; Cost, M.; Pathak, S.; Klintberg, L. E.; Jarausch, D.D.; Higler, R.; Huttner, S.; Leijtens, T.; Stranks, S. D.; Snaith, H. J.; Atature, M.; Phillips, R. T.; Buddy, R. H. J. Phys. Chem. Lett. 2014, 5, 1421-1426. (25) Tan, Z.-K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.; Deschler, F.; Price tag, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D.; Hanusch, F.; Bein, T.; Snaith, H. J.; Pal, R. H. Nat. Nanotechnol. 2014, 9, 687-692. (26) Ueng, H. Y.; Hwang, H. L. J. Phys. Chem. Solids 1989, 50, 1297- 1305. (27) Huang, L.; Zhu, X.; Publicover, N. G.; Hunter, K. W.; Ahmadiantehrani, M.; de Bettencourt-Dias, A.; Bell, T. W. J. Nanopart. Res. 2013, 15, 2056. (28) De Trizio, L.; Prato, M.; Geno.
