Evaluating Cu₂SnS₃ Nanoparticle Layers as Hole-Transporting Materials in Perovskite Solar Cells

Abstract

We investigate the use of simple nontoxic Cu 2 SnS 3 (CTS) nanoparticles (NPs) as low-cost dopant-free hole-transport materials (HTMs) a substitute for spiro-OMeTAD in an n-ip mesoscopic architecture of perovskite solar cells (PSCs). Besides, this work confirms the critical role of the crystalline phase of CTS NPs on the performance of the device. Using a facile one-pot heating-up procedure, pure zincblende and wurtzite structures of CTS NPs were obtained by sulfur element and thiourea as the sulfur source, respectively, and were dispersed in chloroform to make very stable nonpolar ink that is compatible with the perovskite. Nanoparticles with the wurtzite crystal phase showed much better photovoltaic performance compared to the zincblende phase with efficiencies of 13.01 and 7.87%, respectively. The efficiency of the reference solar cell using spiro-OMeTAD was 16.01%. Results from impedance spectroscopy and external quantum efficiency show that by switching from wurtzite-CTS to zincblende-CTS, the resistance of charge transfer at the perovskite/HTM interface is increased, which matches with the descending trend of fill factor of the corresponding cells. According to the morphological characteristics and electrical properties of HTM layers, the better performance of wurtzite-CTS in comparison with zincblende-CTS is due to two factors: (i) enhancement of the band-gap energy and alignment of the valance band maximum; and (ii) uniform smooth coverage of the perovskite film by monodispersed wurtzite-CTS NPs.

Recent Advances in Nanostructured Inorganic Hole-Transporting Materials for Perovskite Solar Cells

“…In addition to the above-mentioned strategies for the design and fabrication of inorganic HTLs, crystal structure regulation and bilayer HTL design have also been reported to boost the PCE and stability of inorganic HTL-based PSCs, although the relevant literature is limited until now. For instance, Heidariramsheh et al successfully synthesized Cu 2 SnS 3 (CTS) NPs with different crystal structures (zincblende and wurtzite) as HTLs for PSCs [ 138 ]. More specifically, zincblende CTS and wurtzite CTS were synthesized by the oil amine solvent heating method using sulfur and thiourea as sulfur sources, respectively.…”

“… Top-view SEM image of various HTLs: ( a ) Spiro-OMeTAD, ( b ) wurtzite-CTS and ( c ) zincblende-CTS with water contact angles on the HTL surface shown inset. Reproduced from [ 138 ], with permission from the ACS Applied Energy Materials, 2021. …”

Enhanced Performance of Planar Perovskite Solar Cells Using Thioacetamide-Treated SnS2 Electron Transporting Layer Based on Molecular Ink

“…Finally, a Au (100 mg) thin film was deposited by thermal evaporation under 2.0 × 10 −5 Torr. The active area of the devices is 0.09 cm 2 . Characterization of Samples.…”

“…Organic–inorganic halide perovskite solar cells (PSCs) have been considered the pioneers of photovoltaic research owing to their high optical absorption, tunable bandgap, high carrier mobility, and excellent photovoltaic performance. − The power conversion efficiency (PCE) of PSCs has risen from 3.8% to 25.7% after a few years − due to the development of so-called advantageous characteristics.…”

Lamination methods for the fabrication of perovskite and organic photovoltaics

“…28,29 Generally, PSCs are composed of the transparent conductive electrode (TCE) and/or transparent conductive oxide (TCO) glass substrate, the electron transporting layer (ETL), perovskite film as the light absorber, the hole transporting layer (HTL), and the metal back contact. [30][31][32][33][34] In the case of OPVs, the conventional structure includes the TCE glass substrate, HTL, light absorber consisting of a bilayer or mixture of p-type (an electron acceptor) and n-type materials (an electron donor), the buffer layer, and metal back contact. 35,36 The ease of device fabrication for both PSCs and OPVs utilizing solution-processed methods such as spin-coating, slot-die coating, or inkjet printing is the key factor in their success.…”