Bifacial tube-type perc solar cell, preparation method thereof, and production device therefor

Abstract

The present invention discloses a bifacial tube-type PERC solar cell, which comprises a rear silver major grid line, a rear aluminum grid line, a rear surface composite film, P-type silicon, an N-type emitter, a front surface silicon nitride film, and a front silver electrode. The present invention also discloses a method and a device for preparing a bifacial tube-type PERC solar cell. The present invention absorbs sunlight on both surfaces, has high photoelectric conversion efficiency, high appearance quality, and high EL yield, and could solve the problems of both scratching and undesirable deposition.

1 . A bifacial tube-type PERC solar cell, wherein it comprises a rear silver major grid line, a rear aluminum grid line, a rear surface composite film, P-type silicon, an N-type emitter, a front surface silicon nitride film, and a front silver electrode; the rear surface composite film, the P-type silicon, the N-type emitter, the front surface silicon nitride film, and the front silver electrode are stacked and connected sequentially from bottom to top;
 the rear surface composite film includes one or more films selected from a group comprising an aluminum oxide film, a silicon dioxide film, a silicon oxynitride film, and a silicon nitride film; it is deposited at a rear surface of a silicon wafer by a tubular PECVD device; the tubular PECVD device is provided with four gas lines of silane, ammonia, trimethyl aluminum, and nitrous oxide; the four gas lines are used alone or in combination to form the aluminum oxide film, the silicon dioxide film, the silicon oxynitride film, and the silicon nitride film; a graphite boat is employed to load and unload the silicon wafer in the tubular PECVD device;   the rear surface composite film forms 30-500 parallel-arranged laser grooving regions by laser grooving; each laser grooving region includes at least 1 set of laser grooving unit; the rear aluminum grid line is connected to the P-type silicon via the laser grooving regions; the rear aluminum grid line is perpendicularly connected to the rear silver major grid line; the pin slot of the graphite boat has a depth of 0.6-0.8 mm; a diameter of a pin base is 6-15 mm, an angle of inclination of an inclined surface of a pin cap is 35-45 degrees; a thickness of the pin cap is 1-1.3 mm.   
     
     
         2 . (canceled) 
     
     
         3 . The bifacial tube-type PERC solar cell according to  claim 1 , wherein 3-5 pin marks are formed on the rear surface of the bifacial tube-type PERC solar cell. 
     
     
         4 . The bifacial tube-type PERC solar cell according to  claim 1 , wherein a bottom layer of the rear surface composite film is the aluminum oxide film, and a top layer is composed of one or more films selected from a group consisting of the silicon dioxide film, the silicon oxynitride film, and the silicon nitride film. 
     
     
         5 . The bifacial tube-type PERC solar cell according to  claim 1 , wherein a bottom layer of the rear surface composite film is the silicon dioxide film; a middle layer of the rear surface composite film is the aluminum oxide film; a top layer is composed of one or more films selected from a group consisting of the silicon dioxide film, the silicon oxynitride film, and the silicon nitride film. 
     
     
         6 . The bifacial tube-type PERC solar cell according to  claim 1 , wherein a thickness of the aluminum oxide film is 5-15 nm, a thickness of the silicon nitride film is 50-150 nm, a thickness of the silicon oxynitride film is 5-20 nm, and a thickness of the silicon dioxide film is 1-10 nm. 
     
     
         7 . A method of preparing the bifacial tube-type PERC solar cell according to  claim 1 , wherein it comprises the following steps:
 S 101 : forming a textured surface on a front surface and a rear surface of the silicon wafer, the silicon wafer is the P-type silicon;   S 102 : performing diffusion on the silicon wafer to form the N-type emitter;   S 103 : removing phosphosilicate glass and peripheral p-n junctions formed during the diffusion; polishing the rear surface of the silicon wafer; the depth of rear surface etching is 3-6 μm;   S 104 : performing annealing on the silicon wafer; an annealing temperature is 600-820° C., a nitrogen flow rate is 1-15 L/min, and an oxygen flow rate is 0.1-6 L/min;   S 105 : depositing the rear surface composite film on the rear surface of the silicon wafer, including the following:
 depositing the aluminum oxide film using TMA and N 2 O; a gas flow rate of TMA is 250-500 sccm, a ratio of TMA to N 2 O is 1 to 15-25; a plasma power is 2000-5000W; 
 depositing the silicon oxynitride film using silane, ammonia, and nitrous oxide; a gas flow rate of silane is 50-200 sccm, a ratio of silane to nitrous oxide is 1 to 10-80; a gas flow rate of ammonia is 0.1-5 slm, the plasma power is 4000-6000W; 
 depositing the silicon nitride film using silane and ammonia; the gas flow rate of silane is 500-1000 sccm; a ratio of silane to ammonia is 1 to 6-15; a deposition temperature of the silicon nitride film is 390-410° C.; a deposition time is 100-400s; the plasma power is 10000-13000W; 
 depositing a silicon dioxide film using nitrous oxide; a gas flow rate of nitrous oxide is 0.1-5 slm; the plasma power is 2000-5000W; 
 the tubular PECVD device is provided with four gas lines of silane, ammonia, trimethyl aluminum, and nitrous oxide; the graphite boat is employed to load and unload the silicon wafer in the tubular PECVD device; the pin slot of the graphite boat has a depth of 0.6-0.8 mm, the diameter of the pin base is 6-15 mm, the angle of inclination of the inclined surface of the pin cap is 35-45 degrees, the thickness of the pin cap is 1-1.3 mm; 
   S 106 : depositing a passivation film on the front surface of the silicon wafer;   S 107 : performing laser grooving at the rear surface of the silicon wafer, wherein a laser wavelength is 532 nm, a laser power is above 14W, a laser scribing speed is above 12 m/s, and a frequency is above 500 kHZ;   S 108 : printing with a paste for the rear silver major grid line on the rear surface of the silicon wafer; drying;   S 109 : printing with aluminum paste at the laser grooving regions to perpendicularly connect with the paste for the rear silver major grid lines;   S 110 : printing with positive electrode slurry on the front surface of the silicon wafer;   S 111 : sintering the silicon wafer at a high temperature to form the rear silver major grid line, the rear aluminum grid lines, and the front silver electrode;   S 112 : performing anti-LID annealing on the silicon wafer to obtain the bifacial tube-type PERC solar cell.   
     
     
         8 . The method according to  claim 7 , wherein depositing the rear surface composite film on the rear surface of the silicon wafer includes the following:
 depositing the aluminum oxide film using TMA and N 2 O; the gas flow rate of TMA is 250-500 sccm, the ratio of TMA to N 2 O is 1 to 15-25; the plasma power is 2000-5000W;   depositing the silicon oxynitride film using silane, ammonia, and nitrous oxide; the gas flow rate of silane is 50-200 sccm, the ratio of silane to nitrous oxide is 1 to 10-80; the gas flow rate of ammonia is 0.1-5 slm, the plasma power is 4000-6000W;   depositing the silicon nitride film using silane and ammonia; the gas flow rate of silane is 500-1000 sccm; the ratio of silane to ammonia is 1 to 6-15; the deposition temperature of the silicon nitride film is 390-410° C.; the deposition time is 100-400s; the plasma power is 10000-13000W;   depositing a silicon dioxide film using nitrous oxide; the gas flow rate of nitrous oxide is 0.1-5 slm; the plasma power is 2000-5000W.   
     
     
         9 . A production device for the bifacial tube-type PERC solar cell according to  claim 1 , the device is the tubular PECVD device, which includes a silicon wafer loading area, a furnace body, a gas cabinet, a vacuum system, a control system, and a graphite boat; the gas cabinet is provided with a first gas line for silane, a second gas line for ammonia, a third gas line for trimethylaluminum, and a fourth gas line for nitrous oxide;
 the graphite boat is employed for loading and unloading the silicon wafer; the graphite boat includes a pin, and the pin includes a pin shaft, a pin cap, and a pin base; the pin shaft is mounted on the pin base; the pin cap is connected to the pin shaft; the pin slot is formed between the pin shaft, the pin cap, and the pin base; the depth of the pin slot is 0.6-0.8 mm; a diameter of the pin base is 6-15 mm; an angle of inclination of an inclined surface of the pin cap is 35-45 degrees; a thickness of the pin cap is 1-1.3 mm.   
     
     
         10 . (canceled)