결정질 실리콘 태양전지의 기술과제 울산대학교 공과대학 첨단소재공학부 교수 천 희 곤 Education & Training Center For Photovoltaic and Wind Power Engineering

태양전지 종류 및 제조 방법

Single Crystalline Solar Cell Front Rear

Multi Crystalline Solar Cell Front Rear

Silicon Solar Cell 구조

Single Crystalline Solar Cell

태양광 System

Photovoltaic Value Chain

PV 기술 적용 사례

Single Crystalline Solar Cell

Single Crystalline Solar Cell

Single Crystalline Solar Cell

태양광 가격 분포

Low-Cost Si Materials for PV

태양전지용 Silicon 원소재 계통도

Wafer Production

Surface Texturing

Cell Process

Basic Steps of Solar Cell

상용 Si 태양전지 개념도

Si 태양전지 효율 최고 기록

Buried Contact Solar Cell

Back Contact Solar Cell Front Rear

Back Contact Solar Cell

Sunpower IBC Solar Cell

Emitter Wrap Through Cell

Laser Fired Contacts Cell

Laser Firing Cell for mc-Si PV

효율 향상 방안

Substrates for Higher Stabilized Efficiency

Law of the Minimum

For Low Cost High Efficiency Si Solar Cell

Rear Surface

Advanced Manufacturing Technology

Metallization Pastes

Common Cell Design

Newer Cell Design

Newer Cell – Complex

Thick Film Patterning Technology Summary

Inkjet Printing

Inkjet Printing

Back Surface Reflector 구조 Overview : 실리콘 태양전지 고도화 표면 passivation 반사방지막 Texturing Emitter Doping Junction isolation Contact Firing 저저항 전극 미세화 Back Surface Reflector 구조 기판 Bowing 방지 Thin Wafer < 200 μm Bulk Surface Field 형성 Bulk & gettering 저저항 전극의 미세 패턴 형성 전극/실리콘의 접촉저항 저감 Selective emitter 구조의 최적화 (cost-effective) 前面 後面/Bulk 후면 반사구조 (BSR) 후면 passivation 및 local contact 구조 최적화 기판품위 향상 (Ga doped p-type, n-type Si)

기술 개발 방향

기술 개발 방향

기술 개발 방향

기술 개발 방향

기술 개발 방향

Introduction PERL Cell OECO Cell 24.5% at sc-Si wafer 23% at mc-Si wafer

Introduction Recent Process Improved Process mc-Si wafer damage removal and texture etching in bath uniform n+ diffusion (dj : 0.3~0.5 micron) PECVD p-SiN anti-reflection coating Electrode by screen print (rear Al, front Ag paste) Co-firing Edge isolation by laser Module RIE Etching Selective Emitter formation Local Back Surface Field Double passivation layer Double screen printing Back Contact Structure

Tecture etching with RIE Process Typical pyramid structure with Chemical Etching Inverted pyramid structure with Reactive Ion Etching Changes of surface statement according to time of process 1min 2min 15min

Tecture etching with RIE Process acidic texture with isotropic ecth alkaline texture with anisotropic etch RIE texture

Selective Emitter Formation 100ohm / □ Emitter High series resistance between metal electrode and emitter Base 20ohm / □ 100ohm / □ Emitter Reduce series resistance between metal electrode and emitter by using Selective Emitter Base

Selective Emitter Formation Schematic cross section of selective emitter Schematic of a one-step selective emitter fabricated by out-diffusion via the gas phase of locally printed rich P-source

Double Screen Printing Diagrams of a conveltional grid electrode with a standard single printing and double printing

Local Back Surface Field

Local Back Surface Field Making local BSF by using laser contact Using Al-Si paste for making back contact Decrease series resistance between rear side and contact Make good ohmic contact

Double Passivation Layer for Rear side UV/Violet Visible Red/IR Typical statement of absorption of sunlight Quantum Efficiency of absorption of sunlight

Double Passivation Layer for Rear side Red/IR + + Rear side of PV Single Layer of BSR ( + ) Back Surface Reflection Red/IR Back Side Electrode Two different layers at the backside: Capture and recycle the photons Reflects more light than the aluminium layer Light reenters the silicon at low angle  light bounces around inside Rear side of PV + Back Surface Passivation First Layer of BSR ( - ) Back Surface Reflection Second Layer of BSR Back Side Electrode +

Back Contact Structure Ribbon ( - ) charge ( + ) charge Each cell has been connecting with ribbon indirectly Each cell will have been connecting with ribbon directly ( + / - ) charge Ribbon ( + ) charge ( - ) charge

Back Contact Structure Metal Wrap Through MWT cell Easy to make modules with solar cells Can reduce series resistance between cells Removing shading area from front bus bar

향후 추진 방향 mc-Si wafer RIE texture etch n+ selective emitter Efficiency PECVD SiNx:H ARC on both sides Local Al-BSF on rear side Front grid double screen printing (~80 μm wide) Double Passivation Layer Back Contact Structure 18% Local BSF Double Passivation Layer Selective Emitter Double Screen Printing 15% RIE Etching Process

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