Functionalized carbon dots on TiO2 for perovskite photovoltaics and stable photoanodes for water splitting

Abstract

Different types of fluorescent carbon nanoparticles, often called carbon dots (CDs), are synthesized by polycondensation and deposited on TiO 2 films to be probed as electron transport layers in organic perovskite photovoltaics and the anode for photoelectrochemical water splitting. Nitrogen CDs, which do not contain oxygen, lead to an increase of around 50 mV in the open circuit voltage of the perovskite cell. All the CD types produce an improved photocurrent in water splitting, particularly CDs that are functionalized with thiol groups and butyl chains. It is demonstrated that the modified electrode is stable under continuous operation for several hours. Other electrochemical characteristics of the electrode, such as the voltammogram shape, onset potentials and open circuit potentials, remain nearly unchanged upon the deposition of CDs. Only the 2 incident photon to current conversion efficiency improves clearly, extending the absorption range by around 20 nm towards longer wavelengths. This study provides new data about mechanisms and electrode arrangements for improving the performance of n-type semiconductors in photovoltaic cells and photoelectrochemical hydrogen production.

Emerging Trends of Carbon‐Based Quantum Dots: Nanoarchitectonics and Applications

“…[293] Recently, Casaos et al demonstrated that CQDs functionalized with thiol groups and butyl chains could be stably deposited on c-TiO 2 /m-TiO 2 electrodes, which increased the absorption edge by ≈20 nm, thereby enhancing the photocurrent by 125%. [294] Wang et al fabricated a nontoxic three-electrode PEC cell using CQDs/TiO 2 film on the FTO as the photoanode, Pt/carbon nanofibers as the counter electrode, and glucose aqueous solution as electrolyte (Figure 10e). [295] An impressive photocurrent density of 4 mA cm −2 at 0.6 V versus RHE was realized (Figure 10f), with substantially improved stability by retaining ≈95% of its initial photocurrent under 10 h of continuous illumination.…”

Plasmonic Copper‐activated ZnO Microarrays for Efficient Photoelectrocatalytic Applications

“…The presence of PCQDs, straddling of band edge potential, high carrier density and hydrophilic nature of the fabricated electrode could be responsible for high photoactivity and thus high photocurrent in the fabricated PCQDs/ZnO-MAs catalyst. [45][46][47][48] The ZnO semiconductor has band gap of 3 eV, and its valence band and conduction band edges are located at À 7.44 and À 4.14 eV, respectively. [49] CQDs have a band gap of around 2.5 eV, and their conduction band and valence band edges are located at around À 3.59 and À 5.92 eV versus vacuum level, respectively.…”

Carbon Nanoparticles as Versatile Auxiliary Components of Perovskite‐Based Optoelectronic Devices

“…pointed out on the improvement of contact angle of TiO 2 ‐based ETL after deposition of a thin layer of CDs modified with o ‐phenylenediamine possessing high nitrogen content. [ 196 ] Gan et al. used nitrogen‐doped GQDs ( Figure a) in planar inverted PSCs with MAPbI 3 as an active layer.…”