An in-situ room temperature route to CuBiI4 based bulk-heterojunction perovskite-like solar cells

Abstract

Both bismuth and copper are non-toxic and earth-abundant elements suitable for lead-free halide perovskite-like photovoltaic devices. Here, we report a highly facile route for in-situ producing copper-bismuth-iodide (CuBiI 4) thin films directly on ITO substrate at room temperature, by utilizing a Bi-Cu alloy layer as precursor. X-ray diffraction and transmission electron microscopy (TEM) results verified the formation of well crystallized CuBiI 4 thin films with [222] orientation. The transient photovoltage (TPV) analysis revealed that the CuBiI 4 is an n-type semiconductor with a suitable band gap of~1.81 eV, preferable to photoelectric conversion compared with CH 3 NH 3 PbI 3. It is very interesting that the subsequent spin-coating process of the classical Spiro-MeOTAD organic solution with TBP and acetonitrile resulted in a dense and smooth CuBiI 4 :Spiro-MeOTAD bulk-heterojunction film. The preliminarily fabricated simple sandwich structures of ITO/CuBiI 4 :Spiro-MeO-TAD/Au hybrid solar cell devices displayed efficient photovoltaic performance with the PCE up to 1.119% of the best sample. The room temperature direct metal surface elemental reaction (DMSER) method may provide a new insight for all-inorganic lead free perovskite-like A a B b X x compounds and high performance photovoltaic devices.

Assessing the Impact of Defects on Lead‐Free Perovskite‐Inspired Photovoltaics via Photoinduced Current Transient Spectroscopy

“…The application of mainstream capacitance-based spectroscopies (e.g., DLTS and TAS) to PIM solar cells would be problematic [47][48][49]66] and may not allow the determination of their defect parameters [66] due to the near-intrinsic character typical of PIMs [26,43,44,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] (Note S1 and Table S1, Supporting Information). This pointed us to the need to pursue alternative current-based spectroscopic approaches.…”

“…[45] However, capacitancebased techniques are particularly problematic in high-resistivity materials, which may have low carrier density (hence a long dielectric relaxation time) as well as low carrier mobility (hence a long transit time). [46][47][48][49] Specifically, capacitance-based defect-level spectroscopies in near-intrinsic semiconductors-as typically the case for PIMs [26,43,44,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] (Note S1, Supporting Information)-are limited by the fact that the charges required for defect-level filling are not readily available in the semiconductor and need to be transported over a finite distance (e.g., from the electrodes). [47][48][49] Additionally, the applicability of DLTS and TAS to perovskites has been recently brought into question.…”

Highly Absorbing Lead-Free Semiconductor Cu2AgBiI6 for Photovoltaic Applications from the Quaternary CuI–AgI–BiI3 Phase Space

“… 26 − 28 Ag 1–3 x Bi 1+ x I 4 and CuBiI 4 have been reported with suitable band gaps of 1.64–1.93 eV; the variation arises from composition, sample type, and assumption of direct or indirect band gaps. 25 , 29 , 30 Devices based on a x = −0.33 Ag 1–3 x Bi 1+ x I 4 (Ag 3 BiI 6 ) solar absorber have reached PCEs of 4.3%, 31 and introducing small amounts of sulfur to the layer has recently been shown to increase the J sc values of devices, increasing the maximum PCE to 5.44(7)%. 32 Cu-containing CuBiI 4 films have also recently been processed into devices reaching PCEs of 1.1%.…”

Single-Source Vapor-Deposited Cs2AgBiBr6 Thin Films for Lead-Free Perovskite Solar Cells

“…However, two challenging problems still need to be solved, namely, lead toxicity and long-term stability issues, for the commercial application of perovskite solar cells (PSCs) [4,5]. Therefore, to date, many researchers have given considerable attention to the development of inorganic and/or environmentally friendly Pb-free perovskite materials to obtain highly stable nontoxic PSC devices [6,7]. A commonly applied approach toward Pb-free perovskites is to replace heavy metal Pb 2+ ions with the divalent metal Sn 2+ ions.…”