Black titanium dioxide (TiO2) quantum dots (QDs) are grown by a solution‐based electrochemical process and an effect of KCl concentration on the growth is investigated. The electrochemical process is demonstrated as a simple one‐step process for the growth of black TiO2 QDs in the solutions via bottom–up process. From the absorption spectra, the absorption appears for an entire visible wavelength (400–700 nm) implying a black TiO2 property. The average size of the black TiO2 QDs is about 4.5 nm from the transmission electron microscopy results and is similar to all KCl concentrations. This indicates that KCl concentration has no effect on the particle size, but has effect on the hydrodynamic size of TiO2 QDs. The black TiO2 QDs can be produced by the hydrogenation process of hydrogen ions during electrochemical process. The obtained black TiO2 QDs can be further explored as an electron‐transporting layer for a perovskite solar cell application.

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Perovskite solar cells (PSCs) have been at the center of attention for research and development of clean energy technology. The platform promises high performance with relatively cheap and low-temperature processing. The main hindrance of the platform is low stability and performance degradation due to humidity. Most defects and degradation often stem from interfaces between the perovskite layer (PSVK) and carrier transporting layer. This work aimed to solve such an issue by improving the interface between the Perovskite layer (PSVK) and electron transporting layer (ETL) made of titanium in the Perovskite solution. That is methylammonium formamidinium lead iodide (FA0.3MA0.7PbI3) PSCs using electrochemical grown TiO2 quantum dots (QDs) mixed in Titanium tetraisopropoxide (TTIP). TiO2 QDs have grown electrochemically in potassium chloride (KCl) solution and then mixed in TTIP with various concentrations (0%, 2.5%, 5.0%, 7.5%, and 10%). The photoconversion efficiency (PCE) of PSCs was improved to 14.05 % while 7.5% of TiO2 QDs passivation with the champion performance of 15.72% (a significant improvement from the 0% standard condition). The PSCs also lasted over 200 hours, demonstrating increased stability with the proposed recipe. This work demonstrated the successful delivery of alkaline passivation using TiO2 QDs as an agent for improving PSCs.