Ultrafast carrier dynamics in bimetallic nanostructure-enhanced methylammonium lead bromide perovskites

Abstract

In this work, we examine the impact of hybrid bimetallic Au/Ag core/shell nanostructures on the carrier dynamics of methylammonium lead tribromide (MAPbBr) mesoporous perovskite solar cells (PSCs). Plasmon-enhanced PSCs incorporated with Au/Ag nanostructures demonstrated improved light harvesting and increased power conversion efficiency by 26% relative to reference devices. Two complementary spectral techniques, transient absorption spectroscopy (TAS) and time-resolved photoluminescence (trPL), were employed to gain a mechanistic understanding of plasmonic enhancement processes. TAS revealed a decrease in the photobleach formation time, which suggests that the nanostructures improve hot carrier thermalization to an equilibrium distribution, relieving hot phonon bottleneck in MAPbBr perovskites. TAS also showed a decrease in carrier decay lifetimes, indicating that nanostructures enhance photoinduced carrier generation and promote efficient electron injection into TiO prior to bulk recombination. Furthermore, nanostructure-incorporated perovskite films demonstrated quenching in steady-state PL and decreases in trPL carrier lifetimes, providing further evidence of improved carrier injection in plasmon-enhanced mesoporous PSCs.

Structural Phase Transitions of Hybrid Perovskites CH3NH3PbX3 (X = Br, Cl) from Synchrotron and Neutron Diffraction Data

“…In addition, its cubic phase and low ionic mobility lead to a better stability under air and moist conditions, compared to the pseudo-cubic CH 3 NH 3 PbI 3 phase, [7,[17][18][19]. Nevertheless, there are some undesirable features to be concerned about in these bromide-based perovskites; it is the case of a larger band gap (2.2 eV), which decreases the solar light absorption [20,21], the relatively large exciton binding energy and the reduced light absorption beyond its band edge at 550 nm (linked to its, previously indicated, larger band gap), associated with more limited efficiencies of CH 3 NH 3 PbBr 3 solar cells [7,18,19,[22][23][24].…”

Plasmon-induced hot electron transfer in AgNW@TiO2@AuNPs nanostructures

“…The small AuNPs could bring external plasmon-phonon coupling to assist the original plasmon induced electron-phonon interaction of silver nanowires and electron transfer, which is similar to the perovskites-TiO 2 injection 56 . The result demonstrates that the fact to have two plasmon modes generates a synergy for a hot electron transfer from silver nanowires and a faster electron injection into TiO 2 .…”

Dual nanocomposite carrier transport layers enhance the efficiency of planar perovskite photovoltaics

“…52 We chose PB1 to study the photobleaching dynamics, because PB2 is primarily dependent on the presence of impurities rather than bulk phase charge transport. 53 Fig . 8(a) displays the results of tting the probe spectrum at wavelengths of 700-745 nm.…”