Chemistry - Publications

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Browsing Chemistry - Publications by Author "Adinolfi, Valerio"
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    Engineering of CH < inf > 3 < /inf > NH < inf > 3 < /inf > PbI < inf > 3 < /inf > Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties
    ( 2016-08-26) Peng, Wei ; Miao, Xiaohe ; Adinolfi, Valerio ; Alarousu, Erkki ; El Tall, Omar ; Emwas, Abdul Hamid ; Zhao, Chao ; Walters, Grant ; Liu, Jiakai ; Ouellette, Olivier ; Pan, Jun ; Murali, Banavoth ; Sargent, Edward H. ; Mohammed, Omar F. ; Bakr, Osman M.
    The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite's three-dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.
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    Heterovalent Dopant Incorporation for Bandgap and Type Engineering of Perovskite Crystals
    ( 2016-01-21) Abdelhady, Ahmed L. ; Saidaminov, Makhsud I. ; Murali, Banavoth ; Adinolfi, Valerio ; Voznyy, Oleksandr ; Katsiev, Khabiboulakh ; Alarousu, Erkki ; Comin, Riccardo ; Dursun, Ibrahim ; Sinatra, Lutfan ; Sargent, Edward H. ; Mohammed, Omar F. ; Bakr, Osman M.
    Controllable doping of semiconductors is a fundamental technological requirement for electronic and optoelectronic devices. As intrinsic semiconductors, hybrid perovskites have so far been a phenomenal success in photovoltaics. The inability to dope these materials heterovalently (or aliovalently) has greatly limited their wider utilizations in electronics. Here we show an efficient in situ chemical route that achieves the controlled incorporation of trivalent cations (Bi3+, Au3+, or In3+) by exploiting the retrograde solubility behavior of perovskites. We term the new method dopant incorporation in the retrograde regime. We achieve Bi3+ incorporation that leads to bandgap tuning (∼300 meV), 104 fold enhancement in electrical conductivity, and a change in the sign of majority charge carriers from positive to negative. This work demonstrates the successful incorporation of dopants into perovskite crystals while preserving the host lattice structure, opening new avenues to tailor the electronic and optoelectronic properties of this rapidly emerging class of solution-processed semiconductors.