Cu₂ZnSnS₄ Quantum Dots as Hole Transport Material for Enhanced Charge Extraction and Stability in All‐Inorganic CsPbBr₃ Perovskite Solar Cells

Abstract

All‐inorganic CsPbBr3 perovskite solar cells (PSCs) have recently generated tremendous interest in next‐generation cost‐effective and stable photovoltaic devices. However, the commonly used costly and unstable organic hole transporting material (HTM) has so far prevented the further development and large‐scale application of PSCs. In this work, Cu2ZnSnS4 quantum dots (CZTS QDs) are exploited as a novel inorganic HTM for CsPbBr3 PSCs. Due to the well‐matched energy levels with the inorganic perovskite layer, a decent power conversion efficiency of 4.84% is achieved, which is quite comparable to the efficiency of the traditional device based on spiro‐OMeTAD HTM (5.36%). Moreover, the photoluminescence (PL) and impedance spectroscopy further demonstrate the more effective hole extraction and transfer properties of the CZTS QDs interface layer, making it a promising material for fabricating efficient and stable PSCs toward practical applications.

Recent Progress of All‐Bromide Inorganic Perovskite Solar Cells

“…Alternatively, QDs can also serve as HTL to replace the expensive organic‐semiconductor materials. For example, Zhou et al used Cu 2 ZnSnS 4 (CZTS) QDs as HTL in CsPbBr 3 PSCs and obtained an efficiency of 4.84% . However, the energy level mismatch was still an issue leading to high recombination rates at the interface.…”

Efficient and Stable All‐Inorganic Perovskite Solar Cells

“…As for the normal all‐inorganic PSCs, the development of high‐performance solution‐processable inorganic HTMs is a huge challenge. To date, some inorganic HTMs have been attempted, such as CuI, [ 35 ] Cu 2 ZnSnS 4 QDs, [ 36 ] Cu(Cr,M)O 2 (M = Ba 2+ , Ca 2+ , or Ni 2+ ) nanoparticles, [ 37 ] Co 3 O 4 , [ 38 ] MnS, [ 39 ] PbS QDs, [ 40 ] CuPc, [ 41 ] etc. Hu et al demonstrated a PCE of 13.21% based on the normal all‐inorganic PSCs with the structure of FTO/c‐TiO 2 /CsPb 0.96 Bi 0.04 I 3 /CuI/Au (Figure 1).…”

“…As for the normal all-inorganic PSCs, the development of highperformance solution-processable inorganic HTMs is a huge challenge. To date, some inorganic HTMs have been attempted, such as CuI, [35] Cu 2 ZnSnS 4 QDs, [36] Cu(Cr,M)O 2 (M ¼ Ba 2þ , Ca 2þ , or Ni 2þ ) nanoparticles, [37] Co 3 O 4 , [38] MnS, [39] PbS Figure 1. Representative efficiency advancements of various PSCs.…”

Compositional Engineering of Chloride Ion‐Doped CsPbBr3 Halides for Highly Efficient and Stable All‐Inorganic Perovskite Solar Cells

“…[ 9,10 ] An innovative method to break this deadlock is to substitute organic cations with inorganic positive ions such as cesium ions to fabricate all‐inorganic cesium lead halide (CsPbX 3 , X = I, Br, and Cl) light‐absorbing material. [ 11–15 ] Among all‐inorganic perovskite halides, the full‐brominated pervoskite CsPbBr 3 with high carrier mobility exhibits excellent moisture and thermal tolerance, causing it to be an ideal light‐harvesting material for stable PSCs. [ 16 ] However, the narrow light absorbance ranges due to the wide bandgap of CsPbBr 3 perovskite and the severe charge recombination at grain boundary and solar cell interfaces caused by the defect states in the perovskite lattice and the mismatch of energy level at CsPbBr 3 /carbon interface make the PCE of the typical carbon‐based CsPbBr 3 PSCs without hole‐transporting layers (HTLs) much lower than that of the mainstream mixed organic–inorganic halide PSCs.…”