TY - JOUR
T1 - Halogen Migration in Hybrid Perovskites
T2 - The Organic Cation Matters
AU - Oranskaia, Aleksandra
AU - Yin, Jun
AU - Bakr, Osman M.
AU - Brédas, Jean Luc
AU - Mohammed, Omar F.
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/9/20
Y1 - 2018/9/20
N2 - In hybrid perovskite materials, the organic cations are one of the key structural components used to tune the electronic and optical properties of this promising class of materials. Here, we studied the strong impact of organic cations, methylammonium (MA) and formamidinium (FA), on halogen vacancy and interstitial migration, as well as surface degradation in cubic-phase MAPbBr3 and FAPbBr3 crystals using density functional theory calculations. We found Br vacancies and interstitials have much lower formation energies and higher density in MAPbBr3 in comparison to FAPbBr3 crystals. Moreover, the transition energy barrier for Br migration through vacancies within the bulk phase is lower in MAPbBr3 than in FAPbBr3. We also found that FAPbBr3 has a much higher rotation barrier of the organic cation than MAPbBr3, which points to a much stronger H-bonding with Br in the former case. Our results show that incorporating organic cations with the appropriate structure, shape, and strong H-bonding capabilities in hybrid perovskite crystals is very beneficial for suppressing ion migration and thus further improving the performance of hybrid perovskite-based devices.
AB - In hybrid perovskite materials, the organic cations are one of the key structural components used to tune the electronic and optical properties of this promising class of materials. Here, we studied the strong impact of organic cations, methylammonium (MA) and formamidinium (FA), on halogen vacancy and interstitial migration, as well as surface degradation in cubic-phase MAPbBr3 and FAPbBr3 crystals using density functional theory calculations. We found Br vacancies and interstitials have much lower formation energies and higher density in MAPbBr3 in comparison to FAPbBr3 crystals. Moreover, the transition energy barrier for Br migration through vacancies within the bulk phase is lower in MAPbBr3 than in FAPbBr3. We also found that FAPbBr3 has a much higher rotation barrier of the organic cation than MAPbBr3, which points to a much stronger H-bonding with Br in the former case. Our results show that incorporating organic cations with the appropriate structure, shape, and strong H-bonding capabilities in hybrid perovskite crystals is very beneficial for suppressing ion migration and thus further improving the performance of hybrid perovskite-based devices.
UR - http://www.scopus.com/inward/record.url?scp=85053202162&partnerID=8YFLogxK
U2 - 10.1021/acs.jpclett.8b02522
DO - 10.1021/acs.jpclett.8b02522
M3 - Article
C2 - 30187754
AN - SCOPUS:85053202162
SN - 1948-7185
VL - 9
SP - 5474
EP - 5480
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 18
ER -