Organic solar cells (OSCs) are considered to be a new generation of phot ovoltaic devices due to many advantages,such as low cost,compatibility with flexible substrates and ease of processing.The small molecule organic material like rubrene is widely used in organic light emitting diode (OLED).In this article, PN cells with the structure of ITO/MoO₃(6nm)/rubrene(30nm)/C₇₀(30nm)/ BCP(6nm)/Al(150nm) and PIN cells with the structure of ITO/MoO₃(5nm)/rubrene(30nm)/rubrene:C₇₀(5nm)/C₇₀(30nm)/BCP(6nm)/Al(150nm) were fabricated.The effect of heat treatment on the performance of two cells is researched by thermal annealing.The experimental results indicate that the shor t-circuit current is up to 3.526mA·cm－2(PN) and 5.413mA·cm－2 (PIN),and the power conver sion efficiencies of these cells are as high as 1.43%(PN) and 2.09%(PIN) with heat treatment,respectively.Contrast with the devices without heat treatment,short-circuit current,filling factor and the power conversion e fficiencies of PN/PIN cells are enhanced by 19.0%,7.1%,28.3% (PN) and 4.8%,20%,24.1% (PIN),respectively.Experime ntal results show that the heat treatment can improve the performance of rubrene/C₇₀ based OSCs.