Abstract: A solar cell (100) includes a photoelectric conversion layer (120) having a front surface (121) and a back surface (123), a back electrode (110) disposed on the back surface (123) of the photoelectric conversion layer (120), a plurality of electrically conductive fingers (130) disposed on the front surface (121) of the photoelectric conversion layer (120), and a plurality of primary bus bars (140) disposed on the front surface (121) of the photoelectric conversion layer (120). Each primary bus bar (140) is electrically connected to a plurality of electrically conductive fingers (130). The solar cell (100) can include from 4 to 12 primary bus bars (140) on the front surface (121) of the photoelectric conversion layer (120) and the primary bus bars (140) on the front surface (121) of the photoelectric conversion layer (120) have a total surface area of at most about 4 cm2.

Abstract: An exemplary screen printing stencil includes a frame, a screen mesh and a metal foil. The screen mesh is stretched tightly in the frame. The metal foil is attached on a surface of the screen mesh. A screen printing pattern is defined on the metal foil by a laser machining process. A machining tolerance of the screen printing pattern is either in a range from 0.005 to 0.02 millimeters or in a range from ?0.02 to ?0.005 millimeters. The screen printing stencil can be used in a screen printing process of manufacturing a printed circuit board, thereby improving quality of the printed circuit board.