Optimal Interfacial Engineering with Different Length of Alkylammonium Halide for Efficient and Stable Perovskite Solar Cells

Abstract

Recently, two‐dimensional (2D) structure on three‐dimensional (3D) perovskites (graded 2D/3D) has been reported to be effective in significantly improving both efficiency and stability. However, the electrical properties of the 2D structure as a passivation layer on the 3D perovskite thin film and resistance to the penetration of moisture may vary depending on the length of the alkyl chain. In addition, the surface defects of the 2D itself on the 3D layer may also be affected by the correlation between the 2D structure and the hole conductive material. Therefore, systematic interfacial study with the alkyl chain length of long‐chained alkylammonium iodide forming a 2D structure is necessary. Herein, the 2D interfacial layers formed are compared with butylammonium iodide (BAI), octylammonium iodide (OAI), and dodecylammonium iodide (DAI) iodide on a 3D (FAPbI3)0.95(MAPbBr3)0.05 perovskite thin film in terms of the PCE and humidity stability. As the length of the alkyl chain increased from BA to OA to DA, the electron‐blocking ability and humidity resistance increase significantly, but the difference between OA and DA is not large. The PSC post‐treated with OAI has slightly higher PCE than those treated with BAI and DAI, achieving a certified stabilized efficiency of 22.9%.

Toward Efficient and Stable Perovskite Solar Cells: Choosing Appropriate Passivator to Specific Defects

“…As the alkyl chain length increasing, the electron‐blocking properties and resistance against humidity of the 3D/2D PSCs were enhanced, whereas the OAI‐treated PSC obtained an optimal PCE of 22.9%. [ 14 ]…”

“…[ 7 ] Especially, after the invention of the first solid‐state PSCs coupling with the solid‐state Spiro‐OMeTAD by Park and coworkers, [ 8 ] the prominent progress has been stridden over the past decade by vigorously manipulating the solvents, [ 9,10 ] compositions, [ 11,12 ] and interfacial modifications. [ 13,14 ] The impressive efficiency not only benefits from the superior properties of perovskite, but also benefits from the affordable material cost and simple processability. All these credits have made PSCs a promising competitor for the next‐generation photovoltaic technology.…”

Guanidinium Passivation for Air‐Stable Rubidium‐Incorporated Cs(1 − x)RbxPbI2Br Inorganic Perovskite Solar Cells

“…Apart from ion substitution, surface passivation is another commonly adopted method to fabricate efficient PSC with superior stability. There are a few reports that use different kinds of organic halide salts, such as guanidinium iodide (GAI), butylammonium iodide (BAI), phenethylammonium iodide (PEAI), octylammonium iodide (OAI), and dodecylammonium iodide (DAI), to passivate the perovskite surface. This can reduce trap density, restrain interface recombination, and increase the hydrophobicity of the perovskite films.…”

A Review on Solution‐Processable Dopant‐Free Small Molecules as Hole‐Transporting Materials for Efficient Perovskite Solar Cells

“…Since the perovskite material tends to degrade when exposed to humidity, light illumination, [15] oxygen, and high temperature, various scientific endeavors have been devoted to improve its stability apart from the encapsulation of the whole device. Introducing alkali metal cations, [16][17][18] such as Cs + and Rb + to partially replace the A + sites of perovskite crystals, doping the perovskite materials with alkylamine small molecules, [6,12,[19][20][21] passivating the surface and/or the bulk of perovskite films with small molecules and polymers, [8,[21][22][23][24][25][26][27] using 2D perovskite materials instead [28][29][30][31] or integrating 2D perovskite into the light absorber, [32][33][34] and substituting all the organic components to inorganic ones [35][36][37][38][39] have been successfully attempted with the result of improved both long-term stability and efficiency for the devices. [40][41][42][43][44] Another stability issue is with the HTLs.…”