Charge transfer rates and electron trapping at buried interfaces of perovskite solar cells

Abstract

Dominating loss mechanisms were identified at hole-selective buried interfaces engineered with carbazole-based self-assembled monolayers between a metal halide perovskite absorber and a conductive metal oxide. The analysis of surface photovoltage transients with a minimalistic kinetic model allowed for the extraction of interfacial electron trap densities and hole transfer rates and their correlation with open-circuit voltages and fill factors of the corresponding highefficiency solar cells is demonstrated.

Damp heat–stable perovskite solar cells with tailored-dimensionality 2D/3D heterojunctions

“…We found that tailoring the dimensionality (n) of the 2D perovskite fragments at the electron-selective interface of inverted PSCs is essential to enable efficient top-contact passivation through 2D perovskite passivation layers. This interface has frequently been ignored because it is assumed that the conventional electron-selective layer, C 60 (or its derivatives), provides sufficient passivation of 3D perovskites (21); instead, attention has predominantly focused on the hole-selective interface of inverted PSCs, situated at the (transparent) bottom contact of the device (22)(23)(24)(25). However, recent reports have revealed that C 60 is only weakly bonded to perovskite layers, which induces a high energetic disorder between perovskite and C 60 layers that limits device performance at elevated operating temperatures (5,6,26).…”

Consistent Interpretation of Electrical and Optical Transients in Halide Perovskite Layers and Solar Cells

“…Instead, various observable quantities are measured as a function of time after photoexcitation, which are more or less closely related to the charge-carrier concentration. These measurable quantities include voltage, [1][2][3] luminescence, [4,5] conductivity [6][7][8] and the amount of free carrier absorption. [9,10] Sometimes, extracted currents in response to a laser pulse are measured as a (relatively) direct assay of charge carriers being extracted as a function of time.…”

Critical Role of Removing Impurities in Nickel Oxide on High‐Efficiency and Long‐Term Stability of Inverted Perovskite Solar Cells

“…According to the redox reaction between the interface of NiO x or NiO x ‐IL HTL and perovskite layer, the amount of Ni 3+ in HTL decreases and the amount of Ni 2+ increases during the reaction process. Therefore, we used lift‐off method (Figure 4g, the details are described in Supporting Information) to concretely study the content changes of Ni 3+ and Ni 2+ in NiO x and NiO x ‐IL buried films after the interfacial reaction for long‐term actual operation (above operational stability measurements: one sun, ambient air, MPP tracking, 1000 h) [59, 61] . As shown in Figure 4h, it is calculated that the ratio of Ni 3+ /Ni 2+ in the control NiO x film decreases from 1.35 to 0.77, while the Ni 3+ /Ni 2+ ratio of NiO x ‐IL film decreases slightly from 1.92 to 1.71.…”