All-inorganic CsPbI3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage Specifically, we develop a hybrid interfacial architecture consisting of CsPbI3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion The champion CsPbI3 quantum dot solar cell has an efficiency of 151% (stabilized power output of 1461%), which is among the highest report to date Building on this strategy, we further demonstrate a highest efficiency of 123% in flexible quantum dot photovoltaics

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Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture.

To fine-tune surface ligands towards high-performance devices, we developed an in situ passivation process for all-inorganic cesium lead iodide (CsPbI3 ) perovskite quantum dots (QDs) by using a bifunctional ligand, L-phenylalanine (L-PHE). Through the addition of this ligand into the precursor solution during synthesis, the in situ treated CsPbI3 QDs display significantly reduced surface states, increased vacancy formation energy, higher photoluminescence quantum yields, and much improved stability. Consequently, the L-PHE passivated CsPbI3 QDs enabled the realization of QD solar cells with an optimal efficiency of 14.62 % and red light-emitting diodes (LEDs) with a highest external quantum efficiency (EQE) of 10.21 %, respectively, demonstrating the great potential of ligand bonding management in improving the optoelectronic properties of solution-processed perovskite QDs.

In situ ligand bonding management of CsPbI 3 perovskite quantum dots enables high-performance photovoltaics and red light-emitting diodes

All-Inorganic CsPbI3 Quantum Dot Solar Cells with Efficiency over 16% by Defect Control

Selective, sensitive, and stable NO2 gas sensor based on porous ZnO nanosheets

Cubic CsPbI3 perovskite quantum dots (PQDs) with ideal optoelectronic properties are promising materials for solution-processed photovoltaics. However, their phase stability suffers from the weakly...

Tuning the Surface-Passivating Ligand Anchoring Position Enables Phase Robustness in CsPbI3 Perovskite Quantum Dot Solar Cells

Metal halide perovskite quantum dots (Pe-QDs) are of great interest in new-generation photovoltaics (PVs). However, it remains challenging in the construction of conductive and intact Pe-QD films to maximize their functionality. Herein, a ligand-assisted surface matrix strategy to engineer the surface and packing states of Pe-QD solids is demonstrated by a mild thermal annealing treatment after ligand exchange processing (referred to as "LE-TA") triggered by guanidinium thiocyanate. The "LE-TA" method induces the formation of surface matrix on CsPbI3 QDs, which is dominated by the cationic guanidinium (GA+ ) rather than the SCN- , maintaining the intact cubic structure and facilitating interparticle electrical interaction of QD solids. Consequently, the GA-matrix-confined CsPbI3 QDs exhibit remarkably enhanced charge mobility and carrier diffusion length compared to control ones, leading to a champion power conversion efficiency of 15.21% when assembled in PVs, which is one of the highest among all Pe-QD solar cells. Additionally, the "LE-TA" method shows similar effects when applied to other Pe-QD PV systems like CsPbBr3 and FAPbI3 (FA = formamidinium), indicating its versatility in regulating the surfaces of various Pe-QDs. This work may afford new guidelines to construct electrically conductive and structurally intact Pe-QD solids for efficient optoelectronic devices.

Guanidinium-Assisted Surface Matrix Engineering for Highly Efficient Perovskite Quantum Dot Photovoltaics.

α-Formamidinium lead iodide (α-FAPbI3) has become one of the most promising candidate materials for high-efficiency and thermally stable perovskite solar cells (PSCs) owing to their outstanding optoelectrical properties and high thermal stability. However, achieving a stable form of α-FAPbI3 where both the composition and the phase are pure is very challenging. Herein, we first report on a combined strategy of precursor engineering and grain anchoring to successfully prepare MA-free and phase-pure stable α-FAPbI3 films. Engineering the precursor solutions by incorporating volatile FA-based additives completely suppresses the formation of non-perovskite δ-FAPbI3 during film crystallization. Grains of the desired α-phase are anchored together and stabilized by permeating 4-tert-butyl-benzylammonium iodide into the α-FAPbI3 film interior via grain boundaries. This cooperative scheme leads to a significantly increased efficiency close to 21% for FAPbI3 perovskite solar cells (PSCs), which is among one of the highest values to date. Moreover, the stabilized PSCs exhibit improved thermal stability and maintained ~90% of their initial efficiency after storing at 50 °C for over 1600 hours. These findings should open new routes towards fabrication of high-quality perovskite films and optoelectronic devices.

Combined Precursor Engineering and Grain Anchoring Leading to MA-Free, Phase-Pure, and Stable α-Formamidinium Lead Iodide Perovskites for Efficient Solar Cells

Chunyang Zhang

Papers

Guanidinium-Assisted Surface Matrix Engineering for Highly Efficient Perovskite Quantum Dot Photovoltaics.

Combined Precursor Engineering and Grain Anchoring Leading to MA-Free, Phase-Pure, and Stable α-Formamidinium Lead Iodide Perovskites for Efficient Solar Cells