Stable High‐Performance Perovskite Solar Cells via Grain Boundary Passivation

Abstract

The trap states at grain boundaries (GBs) within polycrystalline perovskite films deteriorate their optoelectronic properties, making GB engineering particularly important for stable high-performance optoelectronic devices. It is demonstrated that trap states within bulk films can be effectively passivated by semiconducting molecules with Lewis acid or base functional groups. The perovskite crystallization kinetics are studied using in situ synchrotron-based grazing-incidence X-ray scattering to explore the film formation mechanism. A model of the passivation mechanism is proposed to understand how the molecules simultaneously passivate the Pb-I antisite defects and vacancies created by under-coordinated Pb atoms. In addition, it also explains how the energy offset between the semiconducting molecules and the perovskite influences trap states and intergrain carrier transport. The superior optoelectronic properties are attained by optimizing the molecular passivation treatments. These benefits are translated into significant enhancements of the power conversion efficiencies to 19.3%, as well as improved environmental and thermal stability of solar cells. The passivated devices without encapsulation degrade only by ≈13% after 40 d of exposure in 50% relative humidity at room temperature, and only ≈10% after 24 h at 80 °C in controlled environment.

Gradient Energy Alignment Engineering for Planar Perovskite Solar Cells with Efficiency Over 23%

“…[36] It is well known that the high-frequency component represents the transfer resistance (R tr ) and the low-frequency component indicates the recombination resistance (R re ). [36] It is well known that the high-frequency component represents the transfer resistance (R tr ) and the low-frequency component indicates the recombination resistance (R re ).…”

Low-temperature, simple and efficient preparation of perovskite solar cells using Lewis bases urea and thiourea as additives: stimulating large grain growth and providing a PCE up to 18.8%

“…32 Yang and coworkers rst used urea and thiourea as additives for CH 3 -NH 3 (MA)PbI 3 derived normal (ITO/TiO 2 ) PSCs, and demonstrated a PCE of 18.25% using an annealing temperature of 100 C. 10 Meng et al used DMSO/urea to increase the PCE of normal devices up to 20.06% with the perovskites (FAPbI 3 ) 0.75 (MAPbI 3 ) 0.17 (MAPbBr 3 ) 0.08 and urea derived antisolvent washing process. 33 Considering the complexity of perovskite compositions and the myriad fabricating parameters involved in the previous process, we explored the urea and thiourea as simple precursor additives for inverted (MAPbI 3Àx -Cl x and MAPbI 3 ) PSCs.…”

Laser‐Generated Nanocrystals in Perovskite: Universal Embedding of Ligand‐Free and Sub‐10 nm Nanocrystals in Solution‐Processed Metal Halide Perovskite Films for Effectively Modulated Optoelectronic Performance

“…As shown in Figure 2e, there is a significant PL quenching for the CsFAMA-Cl-CDs film due to charge extraction at the perovskite/Cl-CDs interface, [25,27,28] suggesting that Cl-CDs could help better charge separation. As shown in Figure 2e, there is a significant PL quenching for the CsFAMA-Cl-CDs film due to charge extraction at the perovskite/Cl-CDs interface, [25,27,28] suggesting that Cl-CDs could help better charge separation.…”

“…[42][43][44] As shown in Figure 2g, the lowest unoccupied molecular orbital (LUMO) level of Cl-CDs estimated from the onset reduction potentials is −4.12 eV, which is nearly equivalent to that of CsFAMA (−4.11 eV, calculated from UPS in Figure S13, Supporting Information). [25] We have also investigated the intrinsic carrier mobility by using the SCLC method ( Figure S14, Supporting Information). Such LUMO level of Cl-CDs is thus beneficial to electron injection from perovskite to Cl-CDs and electron transfer from Cl-CDs to perovskite, owing to the matched energy level (Figure 2h) as well as the high carrier mobility of Cl-CDs.…”

“…small molecules, [22][23][24] polymers, [19] and semiconductor molecules [25] have been developed to improve the conversion efficiency and the stability of PSCs. By virtue of the advances in conductivity as well as the functionality (such as magnetics, optics, and electronics), metal/semiconductor nanocrystals [26][27][28][29][30][31] are anticipated to provide more spaces to regulate the physical/ chemical features of the perovskite films if embedding the perovskite films with them than that of passivation molecules.…”