Bandgap aligned Cu12Sb4S13 quantum dots as efficient inorganic hole transport materials in planar perovskite solar cells with enhanced stability

Abstract

With the rapid development of perovskite solar cells (PSCs), it is critical to explore efficient and low-cost inorganic hole transport materials (HTMs) to solve the instability issue of the traditional organic HTM spiro-OMeTAD. Herein, Cu₁₂Sb₄S₁₃ quantum dots (QDs) are applied as inorganic HTMs in n–i–p planar PSCs, the bandgap aligned the QDs is achieved by the modulation of the QD size to accelerate hole transport from the perovskite layer to QDs, and a power conversion efficiency (PCE) of 14.13% is achieved for 5.7 nm sized QDs. IPCE and UV-vis spectra indicate that the light absorption intensity of Cu₁₂Sb₄S₁₃ QD based PSCs is slightly higher than that of the spiro-OMeTAD based one, which enables the enhancement of J_SC (21.85 mA cm⁻²) for PSCs. The excellent hole transport behavior of Cu₁₂Sb₄S₁₃ QDs proves that Cu₁₂Sb₄S₁₃ QDs may be considered as an efficient and potential candidate of HTMs in PSCs. Moreover, the stability of the Cu₁₂Sb₄S₁₃ QD based PSCs is significantly improved compared with that of the spiro-OMeTAD based one due to the high stability of Cu₁₂Sb₄S₁₃ QDs and 91% of the initial PCE is retained after 30 days in ambient air.