Hydroxyl‐Rich d‐Sorbitol to Address Transport Layer/Perovskite Interfacial Issues toward Highly Efficient and Stable 2D/3D Tin‐Based Perovskite Solar Cells

Abstract

Organic-inorganic hybrid perovskite solar cells (PSCs) based on tin (Sn) have attracted widespread attention due to their excellent optical and electrical properties similar to lead (Pb)-based analog and more importantly, these Sn-based perovskites owning intrinsic low-toxicity features have broader commercial application prospect. [1][2][3] And compared to Pb-based analog, Sn-based perovskite features a smaller optical bandgap and a more rapid charge-carrier mobility, both of which enable it to absorb more incident solar light and convert the light into more free carriers and then efficiently transport these carriers toward electrodes of PSCs. [3][4][5][6][7][8][9] Unfortunately, Sn-based perovskites suffer from fast oxidation of Sn 2+ to Sn 4+ and poor stability issue. [3,[9][10][11][12][13][14] Low open-circuit voltage (V oc ) also limits further increase of this kind of PSCs in power conversion efficiency (PCE). [15][16][17][18] Dimensionality adjustment from 3D to 2D or 2D/3D mixing is an effective strategy to significantly enhance stability, V oc , or even film morphology. [19][20][21][22][23][24][25] Relative to their 3D analogs, 2D or quasi-2D perovskites possess superior long-term durability and moisture tolerance since they own layered structure consisting of one or several layers of octahedra sandwiched between hydrophobic organic ligands, e.g., butylammonium and phenylethylammonium (PEA), and these hydrophobic organic ligands can protect the perovskite material from moisture and oxygen penetration. [18,[24][25][26][27][28] However, the presence of these organic spacer cations leads to the anisotropy characteristics of the crystal. The inclusion of 2D and quasi-2D perovskite quantum wells affects carrier transport and seriously blocks the charge transport along the vertical direction, which greatly reduces the device performance. [28][29][30][31][32][33][34] Therefore, manipulation of the growth crystallization of low-dimensional tin-based perovskites toward perpendicular orientation to the substrate surface is vital and some coadditives, e.g., NH 4 Cl, [35] PEA cations, [26,36] or cosolvent like N,N-dimethylformamide (DMF) [37] have been added to form preferential orientation perpendicular to the substrate. 2D/3D mixed tin (Sn)-based perovskites serving as excellent active layers possess a potential for enhancing film/device stabilities, open-circuit voltage, and power conversion efficiency (PCE) of perovskite solar cells (PSCs).Unfortunately, the poor morphology and low film coverage of these 2D/3D perovskites jeopardize their device performance and stability. Herein, doping of hydroxyl-rich d-sorbitol into hole transport layer poly(3,4-ethenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) can effectively address the PEDOT:PSS/perovskite interfacial issues. The multihydroxyl groups from d-sorbitol can sufficiently anchor iodide ions ([SnI 6 ] 4− or free I − ) of PEA 0.1 (FA 0.75 MA 0.25 ) 0.9 SnI 3 perovskite via hydrogen bond, which not only introduces more nucleation sites with improved crystall...

A Bifunctional Carbazide Additive For Durable CsSnI3 Perovskite Solar Cells

“…Sn 2+ is easily oxidized to Sn 4+ , accompanied by the phase instability of CsSnI 3 perovskite, leading to rapid degradation of its performance. [32][33][34] It is an urgent need to find a new approach to simultaneously improve the stability and PCE of CsSnI 3 PSCs.…”

Enhancing the performance of tin-based perovskite solar cells through solvent purification of tin iodide

“…Therefore, the lm based on toluenewashed SnI 2 had the lowest amount of Sn 4+ impurities, which can trap photon-generated carriers and should be avoided. 45 The above results prove that the use of high-purity SnI 2 could improve the lm morphology, optical properties, and crystalline quality, and decrease the content of detrimental Sn 4+ impurities, all of which are highly related to solar cell performance.…”

Mitigating Voc Loss in Tin Perovskite Solar Cells via Simultaneous Suppression of Bulk and Interface Nonradiative Recombination

“…It is observed that both the control and EABr-containing perovskite samples show continuous films. The control perovskite film exhibits noncompact morphology with a certain number of surface fluctuations, which may lead to a multitude of charge trap sites as recombination centers, impeding effective carrier transport and extraction and resulting in severe leakage currents, thus reducing device performance. , Moreover, these defects may act as oxidation sites for Sn 2+ which would produce more tin vacancies, leading to more severe nonradiative recombination Figure S2 present SEM images of 2% and 8% EABr-containing perovskite films.…”