Unveiling the Effects of Hydrolysis‐Derived DMAI/DMAPbI_x Intermediate Compound on the Performance of CsPbI₃ Solar Cells

Abstract

Introducing hydroiodic acid (HI) as a hydrolysis‐derived precursor of the intermediate compounds has become an increasingly important issue for fabricating high quality and stable CsPbI3 perovskite solar cells (PSCs). However, the materials composition of the intermediate compounds and their effects on the device performance remain unclear. Here, a series of high‐quality intermediate compounds are prepared and it is shown that they consist of DMAI/DMAPbIx. Further characterization of the products show that the main component of this system is still CsPbI3. Most of the dimethylammonium (DMA+) organic component is lost during annealing. Only an ultrasmall amount of DMA+ is doped into the CsPbI3 and its structure is stabilized. Meanwhile, excessive DMA+ forms Lewis acid–base adducts and interactions with Pb2+ on the CsPbI3 surface. This process passivates the CsPbI3 film and decreases the recombination rate. Finally, CsPbI3 film is fabricated with high crystalline, uniform morphology, and excellent stability. Its corresponding PSC exhibits stable property and improved power conversion efficiency (PCE) up to 17.3%.

Crystallization Kinetics in 2D Perovskite Solar Cells

“…3D perovskites generally have the chemical formula ABX 3 . Figure 1a shows six X-position atoms forming an octahedral structure, where B-position atoms are located at the center of the octahedron, with [BX 6 ] 4− octahedrons corner-sharing with each other and the A cation occupying the voids made by the anionic framework.…”

“…Perovskite has attracted significant interest owing to its high light absorption coefficients, long carrier lifetime and, diffusion length, as well as designable composition and characteristics, [1][2][3][4][5][6] for third-generation solar cells. [7][8][9][10][11][12] As a result of intensive research, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has rapidly risen from the original 3.8% to current 25.2% over the past ten years.…”

Efficient and Stable All‐Inorganic Perovskite Solar Cells

“…However, the influence mechanism of DMAI residue for device stability was not revealed in this work, which remains investigated deeply in the subsequent research work. Although huge progresses have been achieved on DMAI, inconsistent conclusions were obtained on its role of DMAI as an additive [12,22,117] or dopant, [77,109] which could be ascribed to different annealing temperatures and times along with different amounts of DMAI and preparation condition (e.g., humidity, oxygen, etc. ).…”

Advances in Phase Stability of Cesium Lead Halide Perovskites

“…k) XPS spectra of the C 1s and N 1s peaks of syn‐CsPbI 3 film before and after etching 300 s. Reproduced with permission. [ 62 ] Copyright 2020, Wiley‐VCH.…”

“…More recently, compositional and phase evolution during the formation of DMA-derived CsPbI 3 films was carefully studied from different perspectives. [61,62] It has been found that using a precursor combination of DMAI/PbI 2 /CsI, DMAPbI 3 and Cs 4 PbI 6 are formed in the as-spun films and crystallize into a hybrid DMA 0.15 Cs 0.85 PbI 3 perovskite after annealing at 180 C for 15 min in N 2 , showing a 1.67 eV bandgap and superior stability (negligible decay in absorbance after exposed to 70-80% RH for 15 h) (Figure 5f-h). The achieved bandgap is close to previously reported β-CsPbI 3 .…”