Interface Engineering to Drive High-Performance MXene/PbS Quantum Dot NIR Photodiode.

The realization of a controllable transparent conducting system with selective light transparency is crucial for exploring many of the most intriguing effects in top-illuminated optoelectronic devices. However, the performance is limited by insufficient electrical conductivity, low work function, and vulnerable interface of traditional transparent conducting materials, such as tin-doped indium oxide. Here, it is reported that two-dimensional (2D) titanium carbide (Ti3 C2 Tx ) MXene film acts as an efficient transparent conducting electrode for the lead sulfide (PbS) colloidal quantum dots (CQDs) photodiode with controllable near infrared transmittance. The solution-processed interface engineering of MXene and PbS layers remarkably reduces the interface defects of MXene/PbS CQDs and the carrier concentration in the PbS layer. The stable Ti3 C2 Tx /PbS CQDs photodiodes give rise to a high specific detectivity of 5.51 × 1012  cm W-1  Hz1/2 , a large dynamic response range of 140 dB, and a large bandwidth of 0.76 MHz at 940 nm in the self-powered state, ranking among the most exceptional in terms of comprehensive performance among reported PbS CQDs photodiodes. In contrast with the traditional photodiode technologies, this efficient and stable approach opens a new horizon to construct widely used infrared photodiodes with CQDs and MXenes.

Efficient Planar Perovskite Solar Cells with Reduced Hysteresis and Enhanced Open Circuit Voltage by Using PW12-TiO2 as Electron Transport Layer.

An electron transport layer is essential for effective operation of planar perovskite solar cells. In this Article, PW12-TiO2 composite was used as the electron transport layer for the planar perovskite solar cell in the device structure of fluorine-doped tin oxide (FTO)-glass/PW12-TiO2/perovskite/spiro-OMeTAD/Au. A proper downward shift of the conduction band minimum (CBM) enhanced electron extraction from the perovskite layer to the PW12-TiO2 composite layer. Consequently, the common hysteresis effect in TiO2-based planar perovskite solar cells was significantly reduced and the open circuit voltage was greatly increased to about 1.1 V. Perovskite solar cells using the PW12-TiO2 compact layer showed an efficiency of 15.45%. This work can contribute to the studies on the electron transport layer and interface engineering for the further development of perovskite solar cells.