Intermediate Phase Enhances Inorganic Perovskite and Metal Oxide Interface for Efficient Photovoltaics

Abstract

We propose an intermediate-phase engineering strategy to achieve the robust interfacial contact by utilizing volatile organic salts. The introduction of organic cations (such as methylammonium and formamidinium) leads to the formation of an organic-inorganic hybrid perovskite intermediate phase in the initial film and promotes the high-quality interfacial contact of all-inorganic perovskite/metal oxide. A champion CsPb(I 0.75 Br 0.25 ) 3 -based device with a power conversion efficiency of 17.0% and an open-circuit voltage of 1.34 V was realized.

Interface Optimization via Fullerene Blends Enables Open‐Circuit Voltages of 1.35 V in CH3NH3Pb(I0.8Br0.2)3 Solar Cells

“…[ 51,52 ] The most notable achievements among wide bandgap perovskites are cells based on compositions such as Cs 0.2 FA 0.8 Pb(I 0.7 Br 0.3 ) 3 , [ 15 ] Cs 0.05 (FA x MA y ) 0.95 Pb(I 0.76 Br 0.24 ) 3 , [ 53 ] Cs 0.17 FA 0.83 Pb(I 0.6 Br 0.4 ) 3 , [ 54 ] and CsPb(I 0.75 Br 0.25 ) 3 . [ 55 ] The bandgaps vary from 1.69 [ 53 ] to 1.845 eV [ 55 ] with efficiencies up to 20.1%, at a bandgap of 1.69 eV and a V oc = 1.21 V. [ 53 ] The V oc fill factor ( FF ) product, a proxy for the voltage at the maximum power point, plotted as a function of E g for the same devices is shown in Figure 1b. The device by Zhang et al.…”

Self‐Crystallized Multifunctional 2D Perovskite for Efficient and Stable Perovskite Solar Cells

“…[ 6,8 ] Also, the volatile organic cation in the 3D perovskite lattice such as methylammonium (MA + ) and formamidinium (FA + ) degrades the stability of the perovskite itself and lifetime of PSCs. [ 9,10 ] In this regard, 2D perovskites have recently received substantial attention as they contain less‐volatile bulkier organic cations, which can trigger passivation effect and lead to better water resistance, resulting in higher PCE and extended long‐term stability of PSCs. Therefore, the deposition of 2D perovskite on top of the 3D perovskite has presented significant enhancement both in PCEs and stability of PSCs because the 3D/2D perovskite can take advantage of features of 2D perovskite while it can maintain the excellent optoelectronic properties of 3D perovskites.…”

Chemically Stable Black Phase CsPbI3 Inorganic Perovskites for High‐Efficiency Photovoltaics

“…Recently, Hagfeldt and co‐workers proposed a similar intermediate‐phase engineering strategy to fabricate a champion CsPb(I 0.75 Br 0.25 ) 3 ‐based PSC achieving a PCE of 17.0% by utilizing volatile organic cation additive of MAAc and FAAc. [ 61 ] In general, the added organic cations can dope into the perovskite lattice to form an OIHP intermediate phase in the initial precursor film. During the thermal annealing, because of the volatilization of the organic composition, free Cs + replaces the doped organic cation and the OIHP intermediate phase transforms to inorganic perovskite phase.…”