Lead halide perovskite quantum dots (PQDs) or more broadly, nanocrystals possess advantageous features for solution-processed photovoltaic devices. The nanocrystal surface ligands play a crucial role in the transport of photogenerated carriers and ultimately affect the overall performance of PQD solar cells. We have demonstrated significantly improved CsPbI 3 PQD synthetic yield and solar cells performance through surface ligand management. The treatment of a secondary amine, di-n-propylamine (DPA), provides a mild and efficient approach to control the surfaces ligand density of PQDs, which has apparently different working mechanism compared to the previously reported surface treatment. Using an optimal DPA concentration, the treatment can simultaneously remove both long chain insulating surface ligands of oleic acid and oleylamine, even for unpurified This article is protected by copyright. All rights reserved.PQDs with high ligand density. As a result, the electrical coupling between PQDs is enhanced; leading to improved charge transport, reduced carrier recombination, and a high power conversion efficiency (PCE) approaching 15% for CsPbI 3 PQD based solar cells. In addition, the production yield of CsPbI 3 PQDs can be increased by a factor of 8. These results highlight the importance of developing new ligand-management strategies, specifically for emerging PQDs to achieve scalable and high-performance perovskite-based optoelectronic devices.All-inorganic perovskite quantum dots (PQDs) exhibit high photoluminescence quantum yields (PLQY), spectrally tunable bandgap, flexible compositional control, and crystalline strain benefits. [1][2][3][4] PQDs are relatively easy to synthesize which opens a route for next generation optoelectronic devices, as well as opportunities for exploring fundamental properties at nanoscale. [5,6] For photovoltaics (PVs), colloidal CsPbI 3 PQD solar cells were first demonstrated with a power

Through constructing polymer-quantum dot bulk heterojunction interfaces, we reported efficient CsPbI3 and FAPbI3 perovskite quantum dot solar cells.

We have successfully demonstrated the effect of a thin organic bulk-heterojunction (BHJ) interlayer on improving the photovoltaic performance of lead sulfide (PbS) colloidal quantum dot (CQD) solar cells. Multiple organic BHJ films with PTB7-Th blending with various N-type acceptors have been introduced as hole-transporting layer (HTL) in PbS solar cells. Significant enhancement in V oc was achieved in the hybrid devices compared to devices based on conventional HTLs like 1,2-ethanedithiol-treated PbS. Systematic characterizations reveal that the hybrid CQD/organic BHJ architecture can effectively modulate the interfacial charge dynamics and lead to enhanced external quantum efficiency, resulting in a champion efficiency of 12.02%. Solution-processed hybrid CQD/organic architecture may become a universal approach to improve the photovoltaic performance and scalability of PbS CQD solar cells.

As effective light absorbers in solar cells, CsPbI3 all-inorganic perovskite quantum dots (QDs) have received increasing attention, benefitting from their suitable optical band gap and thermal stability. However, the easy cubic to yellow orthorhombic phase transition hinders their further application in stable photovoltaic devices. CsPbBr3 QDs have been targeted as a promising material for ultrahigh voltage and stable solar cells. In this work, we first develop a simple yet efficient post-treatment method using guanidinium thiocyanate (GASCN), which is able to exchange the native capping ligands of CsPbBr3 QDs, thus improving the carrier transport properties through enhanced electrical coupling between QDs. Additionally, the morphology and crystalline properties of solid QD films are also improved. Therefore, simultaneously improved open-circuit voltage (V oc), short-circuit current density (J sc), and fill factor (FF) were obtained in the corresponding CsPbBr3 QD devices. Finally, the QD solar cells based on optimal hole-transporting layers delivered the highest efficiency exceeding 5% together with an ultrahigh V oc of 1.65 V, representing the most efficient CsPbBr3 QD solar cells to date. More importantly, the CsPbBr3 perovskite QD solar cells developed here exhibit excellent stability, ultrahigh voltage, and high transparency over the entire visible spectrum region, demonstrating their great potential in applications like solar windows of greenhouse and hydrogen generation driven by perovskite solar cells.

The unstable PbSe quantum dot (QD) surface requires tedious and complicated synthetic protocols and renders them substantially underdeveloped compared to PbS QDs. Here, we describe a direct synthesis of PbSe QD inks at room temperature. In comparison to the conventional three-step synthesis, our strategy simplifies the fabrication process to one step and reduces the preparation cost by a factor of eight. A photovoltaic device based on these PbSe QD inks has achieved a photovoltaic conversion efficiency (PCE) of 10.38% with high device stability, which is one of the highest PCEs for all reported PbSe QD solar cells. More importantly, the obtained ink has demonstrated the best colloidal stability by far compared with all the reported lead chalcogenides (PbX) QD inks for photovoltaic application. This simple and low-cost synthesis will facilitate ink storage and transport and may ignite a new round of research efforts on the optoelectronic applications of PbSe QDs.