Carbon-based inorganic CsPbX 3 (X = I, Br, Cl) perovskite solar cells (PSCs) are attracting great attention in the photovoltaic field because of their low cost, simple process, and superior thermal stability. However, the large difference in energy band between the CsPbX 3 and carbon electrode leads to the poor hole extraction and unfavorable charge recombination, thus deteriorating device's efficiency. In this work, a solution-processed dopant-free tin phthalocyanine (SnPc) film is used as a hole-transport layer (HTL) to fabricate carbon-based CsPbI 2 Br PSCs by a low-temperature process. At the optimal process, the device achieves a maximum efficiency of 11.39% with less hysteresis, which is much higher than 9.22% of reference device without the SnPc HTL. Moreover, the unencapsulated device exhibits the improved stability and remains about 90% of its initial efficiency after 30 days in ambient air (20−25 °C) with 25−35% relative humidity (RH). This finding reveals that the solution-processed dopant-free SnPc HTL can significantly promote charge transport and suppress charge recombination at the CsPbI 2 Br/carbon interface. This work provides a low-temperature and solutionprocessed method to fabricate the efficient and stable carbon-based inorganic PSCs.

In this work, 4-bromoaniline (BrAL) is employed to modify the CsPbI2Br/carbon electrode interface to passivate defects of all-inorganic CsPbI2Br perovskite solar cells (PSCs). The effects of BrAL modification on the structure, light absorption, and trap-state density (N trap) of CsPbI2Br films and the carrier recombination process, photoelectrical characteristics, and air stability of the PSCs are systematically studied. The results show that the hydrophobic BrAL interlayer modification can lead to a better matched energy-level alignment, reduce the N trap to construct uniform CsPbI2Br films, and suppress carrier recombination to promote charge transport and collection. Thus, the modified PSC achieves a higher power conversion efficiency (PCE) of 11.34% with less hysteresis (reference-PSC, 9.50%) and better stability in ambient air. The BrAL passivation provides a good strategy to enhance the photoelectrical performance and air stability of all-inorganic PSCs.

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The nanostructured ZnO/copper oxide (Cu2O) photovoltaic devices based on electrospun ZnO nanofibrous network and electrodeposited Cu2O layer have been fabricated. The effects of the pH value of electrodeposition solution and the Cu2O layer thickness on the photovoltaic performances have been investigated. It is revealed that the pH value influences the morphology and structure of the Cu2O layer and thus the device performances. The Cu2O layer with an appropriate thickness benefits to charge transfer and light absorption. The device prepared at the optimal conditions shows the lowest recombination rate and exhibits a power conversion efficiency of ~0.77 %.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1169-8) contains supplementary material, which is available to authorized users.