Analysis of Iodide Transport on Methyl Ammonium Lead Iodide Perovskite Solar Cell Structure Through Operando Hard X-ray Photoelectron Spectroscopy

Abstract

To analyze the dynamic of ion species through a MAPbI3–x Cl x (HaP) solar cell, an operando hard X-ray photoelectron spectroscopy (HAXPES) study was proposed. Stacked Au/Ag/AZO/PCBM/HaP/NiO/ITO/glass structures, where AZO, PCBM, NiO, and ITO stand for Al-doped zinc oxide, phenyl-C61-butyric acid methyl ester, nickel oxide, and indium tin oxide, respectively, were evaluated. Experimental core level analysis under an applied bias voltage highlighted that a certain threshold voltage (above the open-circuit voltage (V OC)) is required to trigger the iodide (I–) migration from the HaP to the adjacent electron and hole transport layers. Study also demonstrated that the diffusion of I– in AZO/PCBM over time is unidirectional and follows the gradient descent in concentration. We observed that the irreversibility of the I– transport leads to the absorption of I– by the Ag layer to form a silver iodide (AgI) compound. Furthermore, this work also pointed out the efficiency of an ITO layer when deposited between Ag and AZO to serve as the ion diffusion barrier layer. Finally, the results demonstrated that the presence of ITO restrains the AgI formation and contributes to improving cell performances.

Surface modification of sputtered NiOx hole transport layer for CH3NH3PbI3 perovskite solar cells

“…9,[11][12][13] In the case of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA) or poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT: PSS) as the HTL, the devices are quickly degraded under continuous illumination. The sputtered NiO x is stable under heat, can protect the ion migration through the interface of NiO x /perovskite, 14,15,[19][20][21][22][23] and act as the filter against UV light in Sun light. However, the power conversion efficiency (PCE) values of the perovskite solar cells based on NiO x are lower compared to the PTAA devices as the HTL.…”

Advancing Efficiency and Stability of Lead, Tin, and Lead/Tin Perovskite Solar Cells: Strategies and Perspectives

“…With the knowledge of materials chemistry and interface engineering, the structural stability under thermal, light, and humidity stress have been investigated to resolve the device stability issues, [13][14][15][16] in addition to enhancement in device performance toward the theoretical limit. [16][17][18][19] All these technical advances in low-cost fabrication methods, high PCEs, and enhanced device stability are driving HPSCs toward commercialization. Yet, the long-term operational stability and toxicity of Pb-HPs have raised concern for their widespread application.…”

“…[ 11,12 ] As for Pb‐HPSCs, recent research has been focused on operational device stability and large‐area submodules. With the knowledge of materials chemistry and interface engineering, the structural stability under thermal, light, and humidity stress have been investigated to resolve the device stability issues, [ 13–16 ] in addition to enhancement in device performance toward the theoretical limit. [ 16–19 ] All these technical advances in low‐cost fabrication methods, high PCEs, and enhanced device stability are driving HPSCs toward commercialization.…”