Composition‐Conditioning Agent for Doped Spiro‐OMeTAD to Realize Highly Efficient and Stable Perovskite Solar Cells

Abstract

The doped Spiro‐OMeTAD hole transport layer (HTL) formed using the lithium bis(trifluoromethane) sulfonimide salt and 4‐tert‐butylpyridine with phenethylammonium iodide surface treatment on a perovskite film has continuously dominated the record power conversion efficiencies (PCEs) of perovskite solar cells (pero‐SCs). However, unstable HTL compositions and iodide salts can cause severe device degradation. In this study, an HTL composition‐conditioning agent (CCA), Spiro‐BD‐2OEG, is designed, which contains a Spiro‐OMeTAD‐like backbone, functional pyridine units, and oligo (ethylene glycol) chains. This finely designed CCA presents good miscibility with Spiro‐OMeTAD and its dopants and acts as a conditioning agent through weak bond interactions. As a result, the CCA‐regulated HTL shows a pinhole‐free and smooth morphology with enhanced Spiro‐OMeTAD ordering and improves dopant stability. In addition, the gradient‐distributed CCA in the HTL can narrow the energy level offset with the valence band of the perovskite. The resultant pero‐SCs exhibit an excellent PCE of 24.19% without any interface treatment and weak size dependence. A remarkable PCE of 22.63% is obtained even for a 1.004‐cm2 device. Importantly, the strategy shows good universality and significantly promotes the long‐term stability of the pero‐SCs based on the classical doped Spiro‐OMeTAD.

Perovskite Grain‐Boundary Manipulation Using Room‐Temperature Dynamic Self‐Healing “Ligaments” for Developing Highly Stable Flexible Perovskite Solar Cells with 23.8% Efficiency

“…To determine the mechanism underlying the observed variations in V oc improvement, transient photovoltage (TPV) measurements were conducted (Figure 4d). The TPV curves are fitted with a biexponential decay function, [47] and the fitting results reveal that the charge recombination lifetime of the flexible Pero-I pero-SCs is longer (6.78 µs) than those of the Pero-Nbased (4.21 µs) and Pero-C-based (3.04 µs) devices. This lifetime observation suggests that the 1D/3D perovskite heterostructure efficiently suppresses the charge recombination processes.…”

Open-circuit voltage loss in perovskite quantum dot solar cells

“…The excessive tBP inside the solid film undergoes slow evaporation and results in pinholes within the HTL. 99,100 The agglomeration and migration of Li x O y are detrimental to the homogeneity of the whole film. [101][102][103] The degradation over time and the de-doping process remain unexplained; hence, the need for a prompt solution arises.…”

Unveiling and Modulating the Interfacial Reaction at the Metal–Hole Conductor Heterojunction toward Reliable Perovskite Solar Cells

“…Perovskite solar cells (PSCs) recently have attracted tremendous research attention and shown great development prospects by demonstrating a certified power conversion efficiency (PCE) of 25.7% which is comparable to that of the state-of-the-art crystalline-silicon solar cells. − In spite of such remarkable photovoltaic performance, the instability issues of PSCs remain a critical limiting factor for their commercial application. − Therefore, great efforts have been made to engineer the functional layers and their interfaces in the devices for further optimization of performance longevity. − …”