One of challenging issues in research on planar perovskite solar cells (PSCs) is to design a device structure as simple as possible with high device performance, being beneficial to decreasing process complexity, improving device stability and reducing fabrication cost. In this work, concerning two categories of configurations, p-CH3NH3PbI3 based hole transporting layer (HTL) free planar PSCs, as well as p-CH3NH3PbI3 based HTL- free and electron transporting layer (ETL) free planar PSCs were modeled and simulated by AFORS-HET software, and the performances of these PSCs were analyzed in detail. Several factors or parameters that influence the performance of PSCs were concerned in the models, such as interface defect layer, trap density of the perovskite layer, series resistance and shunt resistance. The yielded power conversion efficiency (PCE) of HTL-free PSCs with the configurations of ZnO:Al/ZnO/CH3NH3PbI3 and ZnO:Al/TiO2/CH3NH3PbI3 were 14.36% and 16.92%, respectively. Three transparent conductive oxide (TCO) materials, i.e. ZnO:Al, FTO and ITO, were directly combined with p-type CH3NH3PbI3 to form ZnO:Al/CH3NH3PbI3, FTO/CH3NH3PbI3 and ITO/CH3NH3PbI3 carrier transporting layer free PSCs, with the PCE up to 15.91%, 15.48% and 6.42%, respectively. This evaluation indicates the high performances of some both HTL-free and ETL-free, carrier transporting layer free, planar PSCs with TCO/perovskite heterojunctions, an extremely simple device structure. This could be because photo-generated carriers can be effectively separated by built-in electric field and transported from p-n heterojunctions to electrodes in TCO/CH3NH3PbI3 heterojunction solar cells.