Activating Old Materials with New Architecture: Boosting Performance of Perovskite Solar Cells with H₂O‐Assisted Hierarchical Electron Transporting Layers

Abstract

The breakthrough of organometal halide perovskite solar cells (PSCs) based on mesostructured composites is regarded as a viable member of next generation photovoltaics. In high efficiency PSCs, it is crucial to finely optimize the charge dynamics and optical properties matching between the perovskites and electron transporting materials to relax the trade‐off between the optical and electrical requirements. Here, a simple antipolar route with H 2 O as the additive is proposed to prepare hierarchical electron transporting layers to boost the efficiency of dopant‐free PSCs. The photovoltaic performance of the PSCs is enhanced owing to increased light‐scattering, improved Ostwald ripening, and photo‐generated electron extraction. Optimization of the H 2 O addition enables a valid power conversion efficiency of 19.9% (reverse scan: 20.02%) to be achieved. The device can retain more than 90% of its initial performance after storage in air more than 30 days. These results are inspiring in that they present that a mesoporous transporting layer could be easily re‐constructed to hierarchical architecture by the antipolar method to further improve the performance of PSCs.

Surface Passivation of Triple-Cation Perovskite via Organic Halide-Saturated Antisolvent for Inverted Planar Solar Cells

“…In classic growth methodologies, the components dissolved by a dimethylformamide (DMF)/dimethyl sulfoxide (DMSO) solvent molecules have a limited gradient concentration between small and large grains, depending on the amount of precursor solution deposited on the substrate; therefore, this method leads to the formation of a final grain with nanometer dimensions. , In the organic halide post-treatment method, the high gradient concentration will lead to accelerating mass transportation between small grains (in treatment solution) and large grains (from precursor solution that is beginning film formation), according to Fick’s first law. Thus, a sufficient amount of small grains (in solution) are redeposited onto the large grains (denucleation of the larger grain) to continue the nucleation process during spin-coating, resulting in microscale final grain sizes. ,− …”

“…This performance deterioration can be the result of the poor charge transport through the excess organic halide, leading to increased ionic migration and subsequent accumulation of ions at the interface layers. The preserved high V oc is due to the low nonradiative losses and suppression of carrier recombination. ,,, The solution concentration for the organic halide post-treatment was optimized in the beginning of this study to be 4 mg/mL in IPA. However, decreasing the concentration to 2 mg/mL was also investigated.…”

Improved efficiency of inverted planar perovskite solar cells with an ultrahigh work function doped polymer as an alternative hole transport layer

“…In this process, mixed HC(NH 2 ) 2 I (FAI) and CH 3 NH 3 Br (MABr) in isopropyl alcohol with 4 mg ml À1 concentration was dropped onto the spinning substrate to enhance the Ostwald ripening of secondary grain growth of the perovskite films. [44][45][46][47][48] In this process, according to Fick's first law, the high gradient concentration will cause faster mass transportation between small grains (in treatment solution) and large grains (from precursor solution that is beginning film formation). 44 As a result, enough small grains in solution are re-deposited onto the large grains (de-nucleation of the larger grain) to enable the nucleation process to continue during spincoating, leading to larger grain sizes.…”

“…44 As a result, enough small grains in solution are re-deposited onto the large grains (de-nucleation of the larger grain) to enable the nucleation process to continue during spincoating, leading to larger grain sizes. [45][46][47][48] More details about the Cs 0.04 (FA 0 . 83 MA 0.17 ) 0.95 Pb(I 0 .…”

Co/Eu co‐doped electron transport layer enhances charge extraction and light absorption for efficient carbon‐based HTM‐free perovskite solar cells

“…18 These methods only increase V oc or FF via improved energy levels 12 or enhanced conductivity, 18 and few strategies can enhance the device parameters simultaneously. 19,20 Therefore, it has a large room of enhancing FF, short-circuit current density (J sc ), and V oc simultaneously in PSCs by boosting the photoelectric performance of ETL. In 2018, Zheng et al developed the cobalt-doped TiO 2 ETL in conventional PSCs by rapid flame method, which need mix CH 4 with air under 1000 C condition.…”