Cesium lead based inorganic perovskite quantum-dots as interfacial layer for highly stable perovskite solar cells with exceeding 21% efficiency

Abstract

Despite the excellent photovoltaic performances of perovskite solar cells (PSCs), the instability of PSCs under severe environment (e.g. humidity, light-induced, etc.) limits further commercialization of such devices. Therefore, in recent years, research on the long-term stability improvement of PSCs has been actively carried out in perovskite field. To address these issues, we demonstrated the incorporation of ultra-thin interfacial layer of inorganic CsPbBr 1.85 I 1.15 perovskite quantum-dots (PQDs) that can effectively passivate defects at or near to the perovskite/hole transport material (HTM) interface, significantly suppressing interfacial recombination. This passivation layer increased the open circuit voltage (V oc ) of triple-cation perovskite cells by as much as 50 mV, with champion cells achieving V oc ∼ 1.14 V. As a result, we obtained hysteresis-free cells with the efficiency beyond 21%. More importantly, devices based on such architecture are capable of resisting humidity and lightinduced. Remarkably, the device employing CsPbBr 1.85 I 1.15 demonstrated a superb shelf-stability aganist to humidity under ambient conditions (R.H.≥40%), retaining nearly 91% of initial efficiency after 30 days, while the efficiency of control device rapidly dropped to 45% from its initial value under the same conditions. Besides benefiting from the high moisture resistivity as well as supressed ion migration, PSCs based on PQDs showed better operational stability (retaining 94% of their initial performance) than that of the PQDs-free one under continuous light irradiation over 400 h. In addition, a faster PL decay time of 4.66 ns was attained for perovskite/PQDs structure (5.77 ns for only PQDs structure) due to the favorable energy transfer at the interface, indicating a Förster resonance energy transfer (FRET) mechanism. This work indicates that inorganic PQDs are important materials as interlayer in PSCs to supremely enhance the device stability and efficiency.

Extending the Photovoltaic Response of Perovskite Solar Cells into the Near‐Infrared with a Narrow‐Bandgap Organic Semiconductor

“…As IEICO‐4F is not directly photoexcited at 374 nm, emission at 855 nm from this blend must stem from its near‐field interactions with CsFAMA. This suite of experiments with neat and blended films confirms FRET in our system, where the excitation energy is transferred from CsFAMA to result in IEICO‐4F emission . We then studied the effects of IEICO‐4F addition on the morphology and crystalline structure of CsFAMA films by employing X‐ray diffraction (XRD) and SEM.…”

Unveiling the Effects of Hydrolysis‐Derived DMAI/DMAPbIx Intermediate Compound on the Performance of CsPbI3 Solar Cells

“…Compared with the emerging photovoltaic materials, halide perovskites with tunable bandgaps, long carrier diffusion, high defect tolerance, superior optical absorption coefficients, and low exciton binding energies are becoming promising materials for solar cells . Due to the intrinsic thermal and light instabilities of cation A in hybrid organic‐inorganic halide perovskite materials, Cs + is the most widely used inorganic cation in the perovskite structure (ABX 3 ) for making up those shortcoming . Among numerous all‐inorganic perovskites, CsPbI 3 has highly efficient optical, electrical properties and appropriate bandgap ( E g = 1.7 eV), which is much ideal for photovoltaic applications …”

New Strategies for Defect Passivation in High‐Efficiency Perovskite Solar Cells

“…Reproduced with permission. [102] Copyright 2019, Elsevier. f) TRPL decays of the bare and QDs-10-modified perovskite films with and without spiro-OMeTAD layer.…”