Investigation of Perovskite Solar Cells Employing Chemical Vapor Deposited Methylammonium Bismuth Iodide Layers

Abstract

Although Pb-based perovskite solar cells already achieve power conversion efficiencies (PCE) beyond 20 %, the use of toxic Pb is causing considerable environmental concern. As a consequence, a variety of alternative cations have been investigated to replace Pb 2+ in the perovskite structure. Methylammonium bismuth iodide (MA 3 Bi 2 I 9 , MBI) has shown promising results for environmentally benign and chemically stable devices. While the PCE of MBIbased solar cells are still comparably low, structural improvements have been made by using chemical vapor deposition (CVD). CVD allows for the well-controlled formation of coherent and dense MBI layers in contrast to solution-processing. In this work, CVD as a possible MBI fabrication method for efficient and size-scalable solar cells is discussed. The precursors MA iodide (MAI) and Bi iodide (BiI 3 ) are deposited in an alternating deposition process forming the desired MBI perovskite on the heated substrate. Substrate temperatures as well as deposition times of each precursor are varied with the aim of forming coherent and dense MBI layers. Optimized films are further processed to solar cell prototypes and compared with solution-processed reference devices. The results reveal that CVD possesses great potential to enable the manufacture of MBI photovoltaic (PV) devices processed in a solvent-free environment.

Fabrication of Methylammonium Bismuth Iodide Layers Employing Methylamine Vapor Exposure

“…PCE (0.174%) as well as the short‐circuit currents (0.695 mA cm −2 ) and open‐circuit voltages (0.595 V) are nearly the same, demonstrating that the exposure to MA is a viable synthesis route. In an earlier study investigating the CVD of MAI and BiI 3 in a similar setup, it was concluded that CVD MBI does not penetrate into the TiO 2 matrix which leads to four times smaller PCE compared with that of solution‐processed cells . In this study, BiI 3 is deposited in advance via solution‐processing and the exposure to MA yields comparable photovoltaic performance.…”

A Review of Perovskite Photovoltaic Materials’ Synthesis and Applications via Chemical Vapor Deposition Method

“…The PCE of the device was 12.4% based on the mesoscopic structure with no hysteresis. Since then, various PMs such as CH 3 NH 3 PbI 3 , (CH 3 NH3) 3 Bi 2 I 9 , and CsPbBr 3 have been successfully prepared in low-pressure or ultra-low-pressure CVD systems [58,59,60,61,62,63,64,65,66,67]. The published works in recent years using the LPCVD method to fabricated perovskite materials are summarized and listed in Table 2.…”