A systematic strategy for effectively engineering the charge extraction in inverted structured perovskite solar cells based on CH₃NH₃PbI_3−xCl_xis provided. An optimized power conversion efficiency of 20.5% is realized.

Dispersive SnS₂ colloidal quantum dots have been synthesized via hot-injection method. Hybrid photovoltaic devices based on blends of a conjugated polymer poly[2-methoxy-5-(3",7"dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) as electron donor and crystalline SnS₂ quantum dots as electron acceptor have been studied. Photoluminescence measurement has been performed to study the surfactant effect on the excitons splitting process. The photocurrent of solar cells with the hybrid depends greatly on the ligands exchange as well as the device heat treatment. AFM characterization has demonstrated morphology changes happening upon surfactant replacement and annealing, which can explain the performance variation of hybrid solar cells.

Reducing damage caused by sputtering of transparent conductive oxide (TCO) electrodes is critical in achieving highly efficient and stable perovskite/silicon tandem solar cells. Here we study the sputter caused damage to bathocuproine (BCP), which is widely used in highly efficient p–i–n structure single junction perovskite solar cells. While the BCP buffer layer protects the underlying layers from damage, it itself can be damaged by sputtering of TCOs at a wide range of target–substrate distances, supported by molecular dynamics simulation. More intriguingly, it is observed that TCO easily peeled off after sputtering when the sputtering target is close to the substrate. This is ascribed to the formation of stress during the cooling down process after sputtering due to different thermal expansion coefficients of the layers. Our studies explain why tin oxide (SnO₂) made by atomic layer deposition can replace BCP for a much better tandem device performance. SnO₂ has high affinity with the sputtered TCO electrode to suppress the peeling-off issue and has higher bond energy to resist sputter induced damage, thus allowing a wider window of target–substrate distances than BCP during TCO sputtering. Ultimately, we demonstrate an efficient perovskite/silicon monolithic tandem solar cell with an efficiency of 26.0% to illustrate the beneficial effects of reduced stress and damage.

Polymer solar cells have shown good prospect for development due to their advantages of low-cost, light-weight, solution processable fabrication, and mechanical flexibility. Their compatibility with the industrial roll-to-roll manufacturing process makes it superior to other kind of solar cells. Normally, indium tin oxide (ITO) is adopted as the transparent electrode in polymer solar cells, which combines good conductivity and transparency. However, some intrinsic weaknesses of ITO restrict its large scale applications in the future, including a high fabrication price using high temperature vacuum deposition method, scarcity of indium, brittleness and scaling up of resistance with the increase of area. Some substitutes to ITO have emerged in recent years, which can be used in flexible polymer solar cells. This article provides the review on recent progress using other transparent electrodes, including carbon nanotubes, graphene, metal nanowires and nanogrids, conductive polymer, and some other electrodes. Device stability is also discussed briefly.

Silicon nanowire (SiNW) arrays show an excellent light-trapping characteristic and high mobility for carriers. Surface plasmon resonance of silver nanoparticles (AgNPs) can be used to increase light scattering and absorption in solar cells. We fabricated a new kind of SiNW/organic hybrid solar cell by introducing AgNPs. Reflection spectra confirm the improved light scattering of AgNP-decorated SiNW arrays. A double-junction tandem structure was designed to manufacture our hybrid cells. Both short-circuit current and external quantum efficiency measurements show an enhancement in optical absorption of organic layer, especially at lower wavelengths.