Dimensionality Controlling of Cs₃Sb₂I₉ for Efficient All‐Inorganic Planar Thin Film Solar Cells by HCl‐Assisted Solution Method

Abstract

sensitivity are the bottlenecks in future commercialization applications. [4,5] Fully-inorganic lead halide perovskites (APbX 3 , A = Cs, Rb, K, etc.), without the organic part affection were expected to resolve the problem of stability. [4,6,7] According to the work of Kubelk et al., fullyinorganic perovskites have similar bandgaps to organo-lead halide analogs and hold much better thermal stability. [4,[7][8][9] Under the scenario of lead-free perovskite, tin (Sn) and germanium (Ge) elements have been considered as hot candidates [10] to replace lead. However, the quick oxidation from Sn 2+ /Ge 2+ to Sn 4+ /Ge 4+ greatly degrades their PCE. [11][12][13] To overcome this problem, heterovalent elements of Sb and Bi were introduced for the implementation of green perovskite. And these perovskite molecular structures transmute from ABX 3 to their derivatives such as A 3 B 2 X 9 .For antimony iodide perovskite (AIP) [14,15] research work, Mitzi and our group combined theoretical calculations, film deposition, and experimental characterizations to understand this new absorber semiconductor. Two kinds of polymorphs exist for Cs 3 Sb 2 I 9 , 0D (dimer) and 2D (layered) phases. Dimer phase exhibits indirect bandgap of 2.50 eV unfavorable for photo voltaics, while layered phase has a direct bandgap of 2.05 eV, a suitable choice as active absorber. The latter one provides similar high level of absorption as CH 3 NH 2 PbI 3 and relatively small in-plane and out-of-plane effective mass. [16][17][18] The layered film could only be synthesized by vapor method with annealing temperature ≈300 °C under the assistance of SbI 3 vapor. [16] Utilizing similar SbI 3 vapor reaction with CsI and SbI 3 precursor film, Chu and co-workers obtained AIP-layered thin film solar cells via a structure of ITO/PEDOT:PSS/AIP/ PC 70 BM/Al and obtained a PCE value of 1.49%. [19] In addition to unique optoelectronic properties, LIP solar cells obtained huge progress highly relying on convenient solution method. The present layered AIP vapor method required high reaction temperature as well as nonuniform composition. Thus, we tried to develop a simple solution method for layered AIP absorbers. According to Zhou and co-workers' theoretical calculations, the AIP dimer phase is an energetically stable Since lead halide perovskite suffers from the obstructions of lead and stability, researchers recently pay more attention to the development of lead-free and stable perovskite absorbers. A typical lead-free antimony iodide perovskite (AIP) is synthesized through vapor reaction at high temperature for photoactive phase. Herein, hydrochloric acid is developed as an intermediate coordinated additive for Cs 3 Sb 2 I 9 photoactive layered phase using HCl-assisted solution method. The uniform and highly crystalline Cs 3 Sb 2 I 9 layered film is obtained by antisolvent engineering. Isopropanol antisolvent is more suitable for present system comparing with traditional lead iodide perovskite-based ones. Physical characterizations manifest the lower trap density, do...

Efficient Copper‐Doped Antimony Sulfide Thin‐Film Solar Cells via Coevaporation Method

“…The black part of the curves at lower bias voltage is an ohmic response, the colored portions in the center are trap-filled limited regimes (V TFL ), and a trap-free SCLC regime at high voltage. [36] The onset voltage of trap-filled limit and trap density are linked according to the following equation…”

Structure, Morphology, and Photovoltaic Implications of Halide Alloying in Lead‐Free Cs3Sb2ClxI9–x 2D‐Layered Perovskites

“…[ 28 ] The same year, Umar et al demonstrated enhanced photovoltaic performance in Cs 3 Sb 2 I 9 using intermediate coordination of Cl ions to form the 2D phase at 160 °C, yet, no Cl − remained in the final film. [ 29 ] Very recently, Peng and co‐workers experimentally verified Jiang's predictions with Cs + at the A‐site; they indeed observed a transition from 0D to 2D at low solution processing temperatures (135 °C) by tuning the initial ratios of I‐ and Cl‐containing precursors and have achieved a PCE of 2.15% for n‐i‐p architecture. [ 30 ] In that work, the Cs 3 Sb 2 Cl x I 9 – x films showed superior photovoltaic properties over pure Cs 3 Sb 2 I 9 , yet, over a variety of substructures, leaving the intrinsic optoelectronic role of Cl − at the X‐site unclear.…”

Incorporating a Polar Molecule to Passivate Defects for Perovskite Solar Cells

“…Lead halide perovskites with strong optical absorption and high carrier mobility have attracted extensive research interest as an excellent light absorber in perovskite solar cells (PSCs) . Although the defects at the film surface and grain boundaries of the perovskite layer inevitably lead to charge recombination and efficiency loss, a lot of effort has been devoted to defect passivation of the perovskite layer, achieving efficiency enhancement .…”