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Impact of monovalent cation halide additives on the structural and optoelectronic properties of CH3NH3PbI3 perovskite

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Abdi-Jalebi, M 
Dar, MI 
Senanayak, SP 
Franckevičius, M 


jats:pThe influence of monovalent cation halide additives on the optical, excitonic, and electrical properties of CHjats:sub3</jats:sub>NHjats:sub3</jats:sub>PbIjats:sub3</jats:sub> perovskite is reported. Monovalent cation halide with similar ionic radii to Pbjats:sup2+</jats:sup>, including Cujats:sup+</jats:sup>, Najats:sup+</jats:sup>, and Agjats:sup+</jats:sup>, have been added to explore the possibility of doping. Significant reduction of sub‐bandgap optical absorption and lower energetic disorder along with a shift in the Fermi level of the perovskite in the presence of these cations has been observed. The bulk hole mobility of the additive‐based perovskites as estimated using the space charge limited current method exhibits an increase of up to an order of magnitude compared to the pristine perovskites with a significant decrease in the activation energy. Consequentially, enhancement in the photovoltaic parameters of additive‐based solar cells is achieved. An increase in open circuit voltage for AgI (≈1.02 vs 0.95 V for the pristine) and photocurrent density for NaI‐ and CuBr‐based solar cells (≈23 vs 21 mA cmjats:sup−2</jats:sup> for the pristine) has been observed. This enhanced photovoltaic performance can be attributed to the formation of uniform and continuous perovskite film, better conversion, and loading of perovskite, as well as the enhancement in the bulk charge transport along with a minimization of disorder, pointing towards possible surface passivation.</jats:p>



additives, CH$_{3}$NH$_{3}$PbI$_{3}$ perovskite, photovoltaics, monovalent cation halide, surface passivation

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Advanced Energy Materials

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EPSRC (via Brunel University London) (unknown)
Engineering and Physical Sciences Research Council (EP/G060738/1)
Department for Business, Energy and Industrial Strategy (EP/M023532/1)
M.A.J. thanks Nyak Technology Limited for a PhD scholarship. M.I.D., S.M.Z., and M.G. thank the King Abdulaziz City for Science and Technology (KACST) and Swiss National Science Foundation (SNSF) for financial support. N.A. gratefully acknowledges financial support from the Swiss confederation under Swiss Government Scholarship program. The authors would like to thank Dr. Pierre Mettraux in Molecular and Hybrid Materials Characterization Center, EPFL for carrying out XPS measurements. A.S. gratefully acknowledges financial support from the Indo-UK APEX project. S.P.S. acknowledges Royal Scociety London for the Newton Fellowship. R.H.F, M.A.J., and A.S. would like to acknowledge the support from EPSRC.