Annealing effects on structural and photovoltaic properties of the dip-SILAR-prepared bismuth oxyhalides (BiOI, Bi7O9I3, Bi5O7I) films

Abstract

Bismuth oxyhalides are becoming a promising contender for photovoltaic applications due to its non-toxic nature and decent optical properties. This study mainly deals with clarifying the effects of phase transformations on the structure, optical, and electrical properties of BiOI thin film prepared via dip-successive ionic layer adsorption and reaction (SILAR) method at different annealing temperatures ranging from 100 to 400 °C. Therefore, significant phase transformations (i.e., the existence of Bi7O9I3 and Bi5O7I have been confirmed at 300 °C and 400 °C, respectively) appeared in the produced films, which were mainly due to the change of annealing temperatures. The experimental results confirmed that produced films achieved the maximum current density and efficiency and minimum current density and efficiency at 100 °C and 400 °C, respectively. Experimental results were also showed that with increasing the annealing temperature from 100 to 400 °C, the indirect bandgap risen from 1.77 to 2.96 eV while the crystallite size decreased from 17.62 to 12.99 nm. The energy band diagram with electrolyte explained the observed poor electrical properties during the phase transformation. Hence, this result will add positive impacts on the new information on findings for the dip-SILAR-prepared BiOI photovoltaic cells.

Influence of chemical interactions on the electronic properties of BiOI/organic semiconductor heterojunctions for application in solution-processed electronics

“…The most commonly reported methods for fabrication of BiOI thin films include the successive ionic layer adsorption and reaction (SILAR) method or vacuum techniques such as chemical vapor deposition (CVD) or aerosol-assisted CVD. 24,30,31,36 Although SILAR 24,36 involves processing from solution, it is not always suitable for formation of heterostructures for application in electronics as it involves extensive and repeated contact with solvents, often results in films with impurities, and requires additional chemicals such as mild acids that can interact chemically with other device layers. For these reasons and to utilize a simple, low-temperature and up-scalable process for the fabrication of BiOI thin films, we adopted the strategy of wet-chemical conversion of spin-coated BiI 3 films for the synthesis of BiOI.…”

“…An exemplary material from this class is that of bismuth oxide iodide (BiOI), which can be synthesized readily and has been largely studied for photocatalysis and photovoltaics in the form of bulk powder or thin films. [24][25][26] However, the anisotropic carrier mobility in BiOI combined with the highly textured morphology of its thin films present significant challenges to enhancing the performance of electronic devices based on BiOI. These challenges are frequently addressed by fabricating epitaxially grown thin films using vapor techniques in vacuum that result in oriented particles with better charge transport properties or by fabricating single-crystal devices.…”

All-solution-processed environment-friendly solid-state BiOI photovoltaic cell with high-short-circuit current by successive ionic layer adsorption and reaction (SILAR)

“…Here, cation source: Bi(NO 3 ) 3 .5H 2 O and anion source: KI and deionized water were used for different SILAR cycle number and after completing the desire cycle number, all the samples have been annealed for 10 min at 100°C. The detailed SILAR procedure and the fundamental material properties of BiOI, such as band gap are reported in our previous papers [10,11,27,28,37]. Here, the investigation of absorber layer morphology has been conducted via a scanning electron microscopy (SEM, JSM-6510).…”

Heavy pnictogen chalcohalides for efficient, stable, and environmentally friendly solar cell applications

“…Here, we regarded that all chalcohalides containing Sb 2+ or Bi 3+ belong to the same type. Thus, we have defined the compounds with chemical formulas of BiOX [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], (Sb, Bi)(S,Se)X , Bi 13 S 18 X 2 [72][73][74], M II 2 SbS 2 I 3 (M II = Sn, Pb) [75][76][77][78][79], and (CH 3 NH 3 )SbSX 2 (MASbSI 2 ) [80] as heavy pnictogen chalcohalide (listed in table 1). Various chalcohalides have been employed in solar cells and their device performance has improved, reaching the highest PCE value of >4% (table 2).…”