Graphdiyne Quantum Dots for Much Improved Stability and Efficiency of Perovskite Solar Cells

Comparing to other carbon materials, the general graphyne structure is much superior in terms of adaptable bandgap, uniformly distributed pores, more design flexibility, easier for chemical synthesis, pliable electronic properties, and smaller atomic density. Herein, novel -graphdiyne quantum dots (GD QDs) are used in perovskite solar cells as a surface modifier or dopant to TiO2, CH3NH3PbI3, and Spiro-OMeTAD to realize multiple advantageous effects, in hoping that it would form a more effective carrier transport channel for boosted solar cell performance. First, the presence of GD QDs on TiO2 surface increases perovskite grain size for higher current density and fill factor. Second, the GD QDs at each interface reduce the conduction band offset, passivate the surface for suppressed carrier recombination to attain higher open-circuit voltage. Third, it improves hydrophobicity and eliminates pinholes in the Spiro-OMeTAD film for enhanced solar cell stability. As a result, the optimized device shows >15% enhancement in power conversion efficiency (from 17.17 to 19.89%) comparing to the reference device. More significantly, the device stability was improved in harsh environment (moist air, UV irradiation, or thermal conditions). It is expected that GD QDs will find their applications in efficient and stable perovskite solar cells and optoelectronic devices.