Blocking effect of morphology-controllable TiO₂ films in carbon-based hole-conductor-free perovskite solar cells

Here, morphology-controllable compact titanium dioxide (CP-TiO₂) films were fabricated on fluorine-doped tin oxide (FTO) substrates as the hole-blocking layers via different ways, including spin coating, magnetron sputtering and atomic layer deposition. A series of planar heterojunction perovskite solar cells (PSCs, FTO/CP-TiO₂/CH₃NH₃PbI₃/C) were constructed using carbon as the counter electrodes in ambient air, which exhibited the advantage of low-cost, highly stable, and holeconductor-free. The CP-TiO₂ films with various morphologies were systematically investigated, which played an important role in the blocking effect and interfacial contact within PSC. Compared with the spin coating and magnetron sputtering methods, the PSCs realized by atomic layer deposition method with free pinholes, high coverage, excellent uniformity and high thermal stability suggest a better efficiency and repeatability in these devices. All these results evidently suggest a feasible route to the design of high-performance heterostructure perovskite solar cells for potential applications in new energy field.