Unveiling Ultrafast Carrier Extraction in Highly Efficient 2D/3D Bilayer Perovskite Solar Cells

Abstract

The development of multidimensional heterostructure (2D/3D) lead halide perovskites has emerged as an effective approach to enhancing the efficiency and long-term stability of perovskite solar cells (PSCs). However, a fundamental understanding of the working mechanisms, such as carrier extraction, and carrier transfer dynamics in the multidimensional perovskites heterostructures remains elusive. Here, we observe the ultrafast carrier extraction in highly efficient 2D/ 3D bilayer PSCs (power conversion efficiency of 21.12%) via femtosecond time-resolved pump−probe transient absorption spectroscopy (TAS). Notably, the formation of quasi-equilibrium states resulting in a subband absorption feature with an ultrafast lifetime of 440 fs was observed, and this feature is found only in 2D/3D perovskite heterostructure. The short-lived feature gives rise to the local electric-field-induced electroabsorption, resulting in an enhanced power conversion efficiency in 2D/3D PSCs. These findings can help comprehend the advanced working mechanism of highly efficient solar cells and other 2D/3D bilayer perovskite-based optoelectronic devices.

Inhibition of ion diffusion/migration in perovskite p–n homojunction by polyetheramine insert layer to enhance stability of perovskite solar cells with p–n homojunction structure

“…The main photobleaching negative peak (PB) at ∼780 nm for all samples was observed clearly, which is attributed to the state-filling of the carriers at the band edge. [45][46][47] In Fig. 2b, the normalized TA spectra of the three types of perovskite samples, from 0.3 to 2 ps after excitation, are exhibited.…”

“…The main photobleaching negative peak (PB) at ∼780 nm for all samples was observed clearly, which is attributed to the state-filling of the carriers at the band edge. 45–47…”

Transformation of Polarization Mechanisms by Dimensional Reduction in Lead-Free Silver Bismuth Bromide Double-Perovskite Thin Films

“…Metal halide perovskites currently develop toward a promising alternative in future energy applications due to their unique properties as semiconducting materials and their ease of processing from solution-based methods. ,− Understanding their contact formation to metal electrodes or other semiconductor layers and the response to an applied voltage plays a crucial role for the possible use in electronic devices such as light-emitting diodes, , thin-film transistors, − or solar cells. − …”

Unraveling Defect-Mediated Enhancement of Transient Photoconductivity and Slower Carrier’s Mobility Decay in Cu-Doped Cs2AgBiBr6 Nanocrystals Using Ultrafast Pump–Probe Spectroscopy

“…Noncontact time-resolved terahertz spectroscopy provides both temporal and spatial resolution, resulting in a more complete molecular understanding of the charge transport processes than direct probe-based approaches . The transient charge carrier mobility and photoconductivity are analyzed after the above-band gap pump laser excitation by directly monitoring the photogenerated charge carriers using the Terahertz (THz) probe . The mobility of charge in a semiconductor depends on a multitude of factors, including the concentration of charge carriers, various types and densities of traps, thermal energies, the existence of scattering sites, among other contributing elements, making it a complex function to characterize .…”

“…12 The transient charge carrier mobility and photo- conductivity are analyzed after the above-band gap pump laser excitation by directly monitoring the photogenerated charge carriers using the Terahertz (THz) probe. 13 The mobility of charge in a semiconductor depends on a multitude of factors, including the concentration of charge carriers, various types and densities of traps, thermal energies, the existence of scattering sites, among other contributing elements, making it a complex function to characterize. 14 As the dynamics of the optically triggered carriers ("photocarriers") directly impact the photovoltaic performance of a solar cell, so it becomes critical to investigate their photocarrier dynamics.…”