Efficient hole-conductor-free organic lead iodide thin film solar cells have been fabricated with a sequential deposition method, and a highest efficiency of 10.49% has been achieved. Meanwhile, the ideal current-voltage model for a single heterojunction solar cell is applied to clarify the junction property of the cell. The model confirms that the TiO 2 /CH 3 NH 3 PbI 3 /Au cell is a typical heterojunction cell and the intrinsic parameters of the cell are comparable to that of the high-efficiency thin-film solar cells. V
Novel large π-conjugated carbon material, graphdiyne (GD), as a dopant to poly(3-hexylthiophene) (P3HT) hole-transporting material (HTM) layer, is introduced into perovskite solar cells for the fi rst time. Raman spectroscopy and ultraviolet photoelectron spectroscopy measurements reveal that relatively strong π-π stacking interaction occurs between GD particles and P3HT (so-called P3HT/GD composite HTM), favorable for the hole transportation and improvement of the cell performance. On the other hand, some GD aggregates exhibit a scattering nature, and thus help to increase the light absorption of the perovskite solar cells in the long wavelength range. As high as 14.58% light-to-electricity conversion effi ciency is achieved, superior to the pristine P3HT-based devices. Additionally, the devices exhibit good stability and reproducibility. Time-resolved photoluminescence decay measurements reveal that the P3HT/GD HTM can accelerate the hole extraction compared with pristine P3HT.
Hybrid organic-inorganic perovskites (e.g., CH3NH3PbI3) are promising light absorbers for the third-generation photovoltaics. Herein we demonstrate a modified two-step deposition method to fabricate a uniform CH3NH3PbI3 capping layer with high-coverage and thickness of 300 nm on top of the mesoporous TiO2. The CH3NH3PbI3 layer shows high light-harvesting efficiency and long carrier lifetime over 50 ns. On the basis of the as-prepared film, TiO2/CH3NH3PbI3 heterojunction solar cells achieve a power conversion efficiency of 10.47% with a high open-circuit voltage of 948 mV, the highest recorded to date for hole-transport-material-free (HTM-free) perovskite-based heterojunction cells. The efficiency exceeding 10% shows promising prospects for the HTM-free solar cells based on organic lead halides.
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