Crystallization Control and Defect Passivation via a Cross-Linking Additive for High-Performance FAPbBr₃ Perovskite Solar Cells

Abstract

Bromine-based hybrid perovskites exhibit excellent performance as the top layer of tandem cells, but their overall efficiency as single-junction devices is still very limited. In this work, trimethylolpropane ethoxylated triacrylate (TET), which can form a cross-linking polymer at the grain boundary after heating at 150 °C, is introduced as an additive in FAPbBr3-based perovskite solar cells. The FAPbBr3 film with TET exhibits pinhole-free crystal grains with a large grain size. With a concentration of 5 mg/mL TET, the average grain size increases from 313 to 505 nm. What is more, Raman spectroscopy and X-ray photoelectron spectroscopy demonstrate that the cross-linked TET has a strong interaction with FAPbBr3, which can passivate the defects of grain boundaries. Therefore, the FAPbBr3-based perovskite solar cells with TET achieve a power conversion efficiency of 8.93%. As we know, this is the highest value in FAPbBr3-based hybrid perovskites with an inverted planar structure. This work provides a new insight into the in situ cross-linking additive TET, which only exists at the grain boundary, does not enter the lattice, and has a crystallization control and defect passivation effect on FAPbBr3 thin films, which will provide a new direction for further improving the performance of FAPbBr3 perovskite solar cells.

Transient Energy-Resolved Photoluminescence Study of Excitons and Free Carriers on FAPbBr3 and FAPbBr3/SnO2 Interfaces

“…Figure b shows the deconvolution considering two components that yielded an R 2 = 0.999. Since FAPbBr 3 is expected to be a pure orthorhombic phase, ,, one can exclude the possibility of the second peak being associated with the mixture of crystalline phases. This also supported the X-ray diffraction pattern presented in Figure S5, consistent with previously published diffractograms. , Another possibility for the doublet is that it relates to defect-related trap states .…”

“…Transient photoluminescence (TRPL) studies are widely used to follow charge recombination decay that provides valuable insights into the charge lifetime and quenching efficiency, which can be correlated with the photovoltaic performance. This is commonly done by single-photon counting, which solely addresses the time component. , In this work, we report a time- and energy-resolved TRPL study utilizing a streak camera with femtosecond pulse excitation. − The results reveal the existence of two emitting states from FAPbBr 3 , which are harnessed differently by the electron transporting layer (ETL) (SnO 2 ) when its surface is treated with KI.…”

“…This is commonly done by single-photon counting, which solely addresses the time component. 23,24 In this work, we report a time-and energy-resolved TRPL study utilizing a streak camera with femtosecond pulse excitation. 25−29 The results reveal the existence of two emitting states from FAPbBr 3 , which are harnessed differently by the electron transporting layer (ETL) (SnO 2 ) when its surface is treated with KI.…”

High‐Efficiency Wide‐Bandgap Perovskite Solar Cells for Laser Energy Transfer Underwater

“…As a result, the film quality of FAPbBr 3 has been considerably optimized, in which the bulk defect has been significantly decreased from 1.15 × 10 22 to 3.32 × 10 15 cm −3 . [ 9,11,15 ]…”

“…[8] Researchers have paid great efforts to decrease the bulk defects by improving the film quality of FAPbBr 3 . [9][10][11][12] Sunil B. Shivarudraiah et al searched the optimum delay time for antisolvent crystallization and adjusted the perovskite film growth by monitoring the in situ photoluminescence (PL). [13] Hu et al studied the solvent-dependent crystallization process of FAPbBr 3 and found the FABr-PbBr 2 -DMSO intermediate inhibited the crystallization process.…”