Silver Bismuth Iodide Nanomaterials as Lead-Free Perovskite for Visible Light Photodetection

Abstract

The synthesis of silver bismuth iodide (SBI) nanocomposite thin films for visible light photodetection application is reported. The formation of different compositions of SBI (AgBiI 4 or Ag 2 BiI 5 ) is achieved by varying the Ag precursor concentration in the solution. Heat treatment of the films at 125 °C for 15 min results in crystalline AgBiI 4 and Ag 2 BiI 5 pin-hole free films and displays uniform coverage of the surface with densely packed grains. The grain sizes in the films are >100 nm for AgBiI 4 and >300 nm for Ag 2 BiI 5 . The direct optical band gaps are 1.63 and 1.66 eV for the AgBiI 4 and Ag 2 BiI 5 films, respectively, making them suitable for light-harvesting applications. The fabricated films exhibit good photodetector responsivity and detectivity under 454 nm light illumination. At 1 V bias, the photoresponsivity of Ag 2 BiI 5 films was 1.25 × 10 5 A/W with specific detectivity of 3.8 × 10 7 Jones. A photocurrent on/off ratio of approximately 39.6, a photoresponse rise time of 1.99 s, and a fall time of 2.04 s were also observed. The Ag 2 BiI 5 perovskite films show better performance for photodetector applications than AgBiI 4 films.

Rudorffites and Beyond: Perovskite‐Inspired Silver/Copper Pnictohalides for Next‐Generation Environmentally Friendly Photovoltaics and Optoelectronics

“…Conventional one-step spin-coating DMSO/DMF Prasad/2021 [38] AgBiI 4 Fd m 3 Sol-gel approach Prasad/2021 [38] Ag 2 BiI 5 R m 3…”

“…[57] Finally, a recent study by Prasad et al highlighted the lowtemperature preparation of high-quality silver bismuth iodide films using aqueous precursor solutions, which are of course highly advantageous from applied and environmental perspectives. [38] The substrate was placed in a solution containing bismuth(III) and silver(I) nitrates along with nitric acid, to which potassium iodide was added to initiate the formation of a silver bismuth iodide film, which occurred over a few hours. The as-prepared films of AgBiI 4 and Ag 2 BiI 5 contained ellipsoidal grains with a size of ≈60-80 nm.…”

“…To investigate the bandgap of Ag-Bi-I thin films, researchers have relied on their optical absorption spectra and density functional theory (DFT) calculations. Compared to bismuth-based hybrid perovskite-inspired materials such as double perovskites and A 3 BiX 9 compounds (where A is a monovalent cation such as Cs + /Rb + /CH 3 NH 3 + and Xis a halide anion such as I -/ Br -/Cl -), which are limited by their wide indirect bandgaps (E g > 2.0 eV), [30,34,36,[125][126][127] Ag-Bi-I materials have a considerably smaller bandgap in the range of 1.55-1.82 eV (indirect) and 1.6-1.93 (direct), [38,39,42,79,90] as determined from the Tauc analysis of their UV-vis absorption spectra, which is more favorable for photovoltaic applications. The wide range in the bandgap of silver bismuth iodides arises from different compositions and synthesis conditions.…”

“…Silver(I)-and copper(I)-based pnictohalides exhibit absorption coefficients over 10 5 cm -1 with direct optical bandgaps in the range of 1.6-2.8 eV, [38][39][40] making them potentially suitable for a range of optoelectronic applications. Furthermore, the reported single-junction solar photovoltaic efficiency of silver pnictohalides has more than quadrupled within just three years from the first solar cell study, increasing from 1.09 ± 0.12% [41,42] to 5.44 ± 0.07%.…”

Tuning the morphology and optoelectronic properties of AgBiI4 film through isopropanol treatment

“…AgBiI 4 , AgBi 2 I 7 , Ag 2 BiI 5 , Ag 3 BiI 6 , AgBi 3 I 10 ), which exhibit the three-dimensional and edge-shared [AgI 6 ] and [BiI 6 ] octahedra structure and have been proven to have good stability and a suitable direct optical band gap for photovoltaic applications (1.63-1.87 eV). [11][12][13][14][15][16] Among them, AgBiI 4 has attracted attention since it is eco-friendly and shows strong thermal stability, photostability, and long-term air stability.…”