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Organic lead halide compounds with perovskite structure become a promising photovoltaic material for lowcost thin film solar cells in recent years. The property of perovskite/metal interface is a fundamental topic for the effective charge transfer at metal electrodes. In this work, we develop an interface modification method of lithium bis(trifluoromethane sulfonimide)(Li TFSI) solution treatment, which can effectively decrease the charge transfer resistance at the CH_3NH_3PbI_(3 –x)Cl_x/Au interface. After the solution treatment, uniform nanodots are formed at the surface of CH_3NH_3PbI_(3–x)Cl_x films, and the barrier height at CH_3NH_3PbI_(3 –x)Cl_x/Au interface reduces from 0.51 V to 0.08 V. As a consequence, the efficiency of hole conductor free solar cells with CH_3NH_3PbI_(3 –x)Cl_x harvester increase from 4.0% to 7.6% under one sun condition. It is also found that the hole conductor free perovskite solar cell can work in a photodetector mode, which has the same output properties with phototransistors. After the Li TFSI solution treatment, the sensitivity of this photodetector can be improved for about one time.
Organic lead halide compounds with perovskite structure become a promising photovoltaic material for lowcost thin film solar cells in recent years. The property of perovskite / metal interface is a fundamental topic for the effective charge transfer at metal electrodes. In this work, we develop an interface modification method of lithium bis (trifluoromethane sulfonimide) (Li TFSI) solution treatment, which can effectively decrease the charge transfer resistance at the CH_3NH_3PbI_ (3 -x) Cl_x / Au interface. After the solution treatment, uniform nanodots are formed at the surface of CH_3NH_3PbI_ (3-x) Cl_x films, and the barrier height at CH_3NH_3PbI_ (3 -x) Cl_x / Au interface reduces from 0.51 V to 0.08 V. As a consequence, the efficiency of hole conductor free solar cells with CH_3NH_3PbI_ (3-x ) Cl_x harvester increase from 4.0% to 7.6% under one sun condition. It is also found that the hole conductor free perovskite solar cell can work in a photodetector mode, which has the same output p After the Li TFSI solution treatment, the sensitivity of this photodetector can be improved for about one time.