Robust Molecular Dipole‐Enabled Defect Passivation and Control of Energy‐Level Alignment for High‐Efficiency Perovskite Solar Cells

Abstract

The ability to passivate defects and modulate the interface energy-level alignment (IEA) is key to boost the performance of perovskite solar cells (PSCs). Herein, we report ar obust route that simultaneously allows defect passivation and reduced energy difference between perovskite and hole transport layer (HTL) via the judicious placement of polar chlorine-terminated silane molecules at the interface. Density functional theory (DFT) points to effective passivation of the halide vacancies on perovskite surface by the silane chlorine atoms.A ni ntegrated experimental and DFT study demonstrates that the dipole layer formed by the silane molecules decreases the perovskite work function, imparting an Ohmic character to the perovskite/HTL contact. The corresponding PSCs manifest anearly 20 %increase in power conversion efficiency over pristine devices and am arkedly enhanced device stability.A ss uch, the use of polar molecules to passivate defects and tailor the IEA in PSCs presents apromising platform to advance the performance of PSCs.

Interface Chelation Induced by Pyridine‐Based Polymer for Efficient and Durable Air‐Processed Perovskite Solar Cells

“…Theincorporation of SHP essentially reduces the trap assisted recombination process and non-radiative losses. [14] As expected, the perovskite films with SHP illustrate stronger absorption than the reference in the full UV-vis spectra. Theutilization rate of solar spectrum in perovskite films improved essentially with the incorporation of SHP.O nt he other hand, time-resolved photoluminescence (TRPL) decay measurements were adopted to investigate the dynamics of charge excitation and recombination.…”

“…Ar ed-shift of PL peak position occurred over time in the pristine perovskite films,w hich mainly attribute to the suppression of trap-assisted recombination. [14,21] Significantly,t he stretching stability and self-healing process were explored to expand the applications of PSCs to portable and flexible electronics fields.A ss hown in Figure 5d(i), the normalized PCE varied within as train of 1% to 30 %a fter stretching for 150 cycles in ambient atmosphere.A se xpected, the self-healed PSCs maintain 80 %o fo riginal PCE while the control device afford an apparent decrease to 50 %. Moreover,c hanges in the PSCs photovoltaic performance under 20 %s train was also investigated (Figure 5d ii), and remarkable stability and selfhealing performance at room temperature were verified for the devices with SHP.C racks at the GBs could be healed by SHP with plenty of hydrogen bonds,a nd the strain resulting from external stress was dissipated.…”

A “double-sided tape” modifier bridging the TiO2/perovskite buried interface for efficient and stable all-inorganic perovskite solar cells

“…[18][19][20][21] Moreover, the band structure and the surface properties of TiO 2 ETLs play a major role in regulating interface energy level matching, interface contact and perovskite lm growth, respectively, which are the key factors that determine the rapid transfer of charge and the minimum recombination of charge to boost PSC performance. 22 Therefore, the surface modication of TiO 2 ETLs with organic or inorganic compounds has been extensively implemented to optimize the interface properties and perovskite growth to promote charge extraction for a higher output of the device PCE. [23][24][25] For instance, Shen et al modied the interface of TiO 2 ETLs and CsPbBr 3 using a metal organic framework material (ZIF-8) to promote the orderly growth of microcrystals inside the perovskite layer and enhance the cohesion between the CsPbBr 3 lm and the porous TiO 2 substrate, which nally resulted in the formation of a high-quality light absorption layer and more perfect energy level alignment to improve the performance of the PSCs.…”

Amidinium additives for high-performance perovskite solar cells

“…17–26 Among them, additive engineering is an effective means to influence the crystallization kinetics of halide perovskites. 21,27–29 A wide range of additives have been previously introduced into the perovskite precursor solution, such as small organic molecules, 30–33 metal halide salts, 34–36 and polymers. 37 Some additive species can improve the crystallization of perovskite, while others passivate defects at perovskite grain boundaries (GBs).…”