We investigate the recombination mechanism in an a-Si/c-Si interface,and analyze the key factors that influence the interface passivation quality,such as Q_s,δ_p/δ_n and D_（it）.The polarity of the dielectric film ...We investigate the recombination mechanism in an a-Si/c-Si interface,and analyze the key factors that influence the interface passivation quality,such as Q_s,δ_p/δ_n and D_（it）.The polarity of the dielectric film is very important to the illustration level dependent passivation quality;when nδ_n = pδ_p and the defect level E_t equal to E_i（c-Si）,the defect states are the most effective recombination center,AFORS-HET simulation and analysis indicate that emitter doping and a-Si/c-Si band offset modulation are effective in depleting or accumulating one charged carrier.Interface states（D_（it）） severely deteriorate V_（oc） compared with J_（sc） for a-Si/c-Si HJ cell performance when D_（it） is over 1×10^（10） cm^（-2）·eV^（-1）.For a c-Si（P）/a-Si（P~＋） structure,φ_（BSF） in c-Si andφ_0 in a-Si have different performances in optimization contact resistance and c-Si（P）/a-Si（P~＋） interface recombination.展开更多
This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si...This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si：H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si：H/μc-Si：H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.展开更多
The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logar...The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).展开更多
Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollutio...Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great change in cell′s structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell′s efficiency. A conversion efficiency of 3.42% has been achieved on 1 cm2 a-Si/c-Si heterojunction solar cell (Isc=16.93 mA, Voc=310.9 mV, FF=0.6493, AM=1.5 G, 24 ℃), while the cell with diffused homojunction only got an efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.展开更多
In order to obtain higher conversion efficiency and to reduce production cost for hydrogenated amorphous silicon/crystalline silicon(a-Si:H/c-Si) based heterojunction solar cells, an a-Si:H/c-Si heterojunction with lo...In order to obtain higher conversion efficiency and to reduce production cost for hydrogenated amorphous silicon/crystalline silicon(a-Si:H/c-Si) based heterojunction solar cells, an a-Si:H/c-Si heterojunction with localized p–n structure(HACL) is designed. A numerical simulation is performed with the ATLAS program. The effect of the a-Si:H layer on the performance of the HIT(heterojunction with intrinsic thin film) solar cell is investigated. The performance improvement mechanism for the HACL cell is explored. The potential performance of the HACL solar cell is compared with those of the HIT and HACD(heterojunction of amorphous silicon and crystalline silicon with diffused junction) solar cells.The simulated results indicate that the a-Si:H layer can bring about much absorption loss. The conversion efficiency and the short-circuit current density of the HACL cell can reach 28.18% and 43.06 m A/cm^2, respectively, and are higher than those of the HIT and HACD solar cells. The great improvement are attributed to(1) decrease of optical absorption loss of a-Si:H and(2) decrease of photocarrier recombination for the HACL cell. The double-side local junction is very suitable for the bifacial solar cells. For an HACL cell with n-type or p-type c-Si base, all n-type or p-type c-Si passivating layers are feasible for convenience of the double-side diffusion process. Moreover, the HACL structure can reduce the consumption of rare materials since the transparent conductive oxide(TCO) can be free in this structure. It is concluded that the HACL solar cell is a promising structure for high efficiency and low cost.展开更多
A novel structure of Ag gridlSiN_(x)/n+-c-Si/n-c-Si/i-a-Si:H/p^(+)-a-Si:HlTCO/Ag grid was designed to increase the ef-ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material c...A novel structure of Ag gridlSiN_(x)/n+-c-Si/n-c-Si/i-a-Si:H/p^(+)-a-Si:HlTCO/Ag grid was designed to increase the ef-ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost.The simulation results show that the new structure obtains higher efficiency compared with the typical bifa-cial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current(J_(sc)),while retaining the advantages of a high open-circuit voltage,low temperature coefficient,and good weak-light performance.Moreover,real cells composed of the novel structure with dimensions of 75 mm×75 mm were fabricated by a special fabrication recipe based on industrial processes.Without parameter optimization,the cell efficiency reached 21.1%with the J_(sc)of 41.7 mA/cm^(2).In addition,the novel structure attained 28.55%potential conversion efficiency under an illumination of AM 1.5 G,100 mW/cm^(2).We conclude that the configuration of the Ag grid/SiN_(x)/n^(+)-c-Si/n-c-Si/i-a-Si:H/p^(+)-a-Si:H/TCO/Ag grid is a promising structure for high efficiency and low cost.展开更多
The damage on the atomic bonding and electronic state in a SiO_x（1.4-2.3 nm）/c-Si（150 μm） interface has been investigated.This occurred in the process of depositing indium tin oxide（ITO） film onto the silicon s...The damage on the atomic bonding and electronic state in a SiO_x（1.4-2.3 nm）/c-Si（150 μm） interface has been investigated.This occurred in the process of depositing indium tin oxide（ITO） film onto the silicon substrate by magnetron sputtering.We observe that this damage is caused by energetic particles produced in the plasma（atoms,ions,and UV light）.The passivation quality and the variation on interface states of the SiO_x/c-Si system were mainly studied by using effective minority carrier lifetime（τ_（eff）） measurement as a potential evaluation.The results showed that the samples＇ τ_（eff）was reduced by more than 90%after ITO formation,declined from 107 μs to 5 μs.Following vacuum annealing at 200 ℃,the τ_（eff） can be restored to 30 μs.The components of Si to O bonding states at the SiO_x/c-Si interface were analyzed by x-ray photoelectron spectroscopy（XPS） coupled with depth profiling.The amorphous phase of the SiO_x layer and the ＂atomistic interleaving structure＂ at the SiO_x/c-Si interface was observed by a transmission electron microscope（TEM）.The chemical configuration of the Si-O fraction within the intermediate region is the main reason for inducing the variation of Si dangling bonds（or interface states） and effective minority carrier lifetime.After an appropriate annealing,the reduction of the Si dangling bonds between SiO_x and near the c-Si surface is helpful to improve the passivation effect.展开更多
基金Project supported by the International Joint Foundation of Shanghai Science & Technology Commission with Applied Material,China(No. 08520741400)the Talent Foundation of Shanghai Science & Technology Commission,China(No.08XD14022)
文摘We investigate the recombination mechanism in an a-Si/c-Si interface,and analyze the key factors that influence the interface passivation quality,such as Q_s,δ_p/δ_n and D_（it）.The polarity of the dielectric film is very important to the illustration level dependent passivation quality;when nδ_n = pδ_p and the defect level E_t equal to E_i（c-Si）,the defect states are the most effective recombination center,AFORS-HET simulation and analysis indicate that emitter doping and a-Si/c-Si band offset modulation are effective in depleting or accumulating one charged carrier.Interface states（D_（it）） severely deteriorate V_（oc） compared with J_（sc） for a-Si/c-Si HJ cell performance when D_（it） is over 1×10^（10） cm^（-2）·eV^（-1）.For a c-Si（P）/a-Si（P~＋） structure,φ_（BSF） in c-Si andφ_0 in a-Si have different performances in optimization contact resistance and c-Si（P）/a-Si（P~＋） interface recombination.
基金Project supported by the State Key Development Program for Basic Research of China (Grant Nos 2006CB202602 and2006CB202603)the National Natural Science Foundation of China (Grant No 60506003)
文摘This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si：H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si：H/μc-Si：H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.
基金Project(11374094)supported by the National Natural Science Foundation of ChinaProject(2013HZX23)supported by Natural Science Foundation of Hunan University of Technology,ChinaProject(2015JJ3060)supported by Natural Science Foundation of Hunan Province of China
文摘The effect of the parameters on the open-circuit voltage, V_(OC) of a-Si:H/c-Si heterojunction solar cells was explored by an analytical model. The analytical results show that V_(OC) increases linearly with the logarithm of illumination intensity under usual illumination. There are two critical values of the interface state density(D_(it)) for the open-circuit voltage(V_(OC)), D_(it)^(crit,1) and D_(it)crit,2(a few 1010 cm^(-2)·e V^(-1)). V_(OC) decreases remarkably when D_(it) is higher than D_(it)^(crit,1). To achieve high V_(OC), the interface states should reduce down to a few 1010 cm^(-2)·e V^(-1). Due to the difference between the effective density of states in the conduction and valence band edges of c-Si, the open-circuit voltage of a-Si:H/c-Si heterojunction cells fabricated on n-type c-Si wafers is about 22 mV higher than that fabricated on p-type c-Si wafers at the same case. V_(OC) decreases with decreasing the a-Si:H doping concentration at low doping level since the electric field over the c-Si depletion region is reduced at low doping level. Therefore, the a-Si:H layer should be doped higher than a critical value of 5×10^(18) cm^(-3) to achieve high V_(OC).
文摘Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great change in cell′s structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell′s efficiency. A conversion efficiency of 3.42% has been achieved on 1 cm2 a-Si/c-Si heterojunction solar cell (Isc=16.93 mA, Voc=310.9 mV, FF=0.6493, AM=1.5 G, 24 ℃), while the cell with diffused homojunction only got an efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB1500403)the National Natural Science Foundation of China(Grant Nos.11964018,61741404,and 61464007)the Natural Science Foundation of Jiangxi Province of China(Grant No.20181BAB202027)
文摘In order to obtain higher conversion efficiency and to reduce production cost for hydrogenated amorphous silicon/crystalline silicon(a-Si:H/c-Si) based heterojunction solar cells, an a-Si:H/c-Si heterojunction with localized p–n structure(HACL) is designed. A numerical simulation is performed with the ATLAS program. The effect of the a-Si:H layer on the performance of the HIT(heterojunction with intrinsic thin film) solar cell is investigated. The performance improvement mechanism for the HACL cell is explored. The potential performance of the HACL solar cell is compared with those of the HIT and HACD(heterojunction of amorphous silicon and crystalline silicon with diffused junction) solar cells.The simulated results indicate that the a-Si:H layer can bring about much absorption loss. The conversion efficiency and the short-circuit current density of the HACL cell can reach 28.18% and 43.06 m A/cm^2, respectively, and are higher than those of the HIT and HACD solar cells. The great improvement are attributed to(1) decrease of optical absorption loss of a-Si:H and(2) decrease of photocarrier recombination for the HACL cell. The double-side local junction is very suitable for the bifacial solar cells. For an HACL cell with n-type or p-type c-Si base, all n-type or p-type c-Si passivating layers are feasible for convenience of the double-side diffusion process. Moreover, the HACL structure can reduce the consumption of rare materials since the transparent conductive oxide(TCO) can be free in this structure. It is concluded that the HACL solar cell is a promising structure for high efficiency and low cost.
基金Project supported by the Jiangxi Provincial Key Research and Development Foundation,China(Grant No.2016BBH80043)the Open Fund of Jiangsu Key Laboratory of Materials and Technology for Energy Conversion,China(Grant No.NJ20160032)the National Natural Science Foundation of China(Grant Nos.61741404,61464007,and 51561022)
文摘A novel structure of Ag gridlSiN_(x)/n+-c-Si/n-c-Si/i-a-Si:H/p^(+)-a-Si:HlTCO/Ag grid was designed to increase the ef-ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost.The simulation results show that the new structure obtains higher efficiency compared with the typical bifa-cial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current(J_(sc)),while retaining the advantages of a high open-circuit voltage,low temperature coefficient,and good weak-light performance.Moreover,real cells composed of the novel structure with dimensions of 75 mm×75 mm were fabricated by a special fabrication recipe based on industrial processes.Without parameter optimization,the cell efficiency reached 21.1%with the J_(sc)of 41.7 mA/cm^(2).In addition,the novel structure attained 28.55%potential conversion efficiency under an illumination of AM 1.5 G,100 mW/cm^(2).We conclude that the configuration of the Ag grid/SiN_(x)/n^(+)-c-Si/n-c-Si/i-a-Si:H/p^(+)-a-Si:H/TCO/Ag grid is a promising structure for high efficiency and low cost.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61274067,60876045,and 61674099)the Research and Development Foundation of SHU-SOENs PV Joint Laboratory,China(Grant No.SS-E0700601)
文摘The damage on the atomic bonding and electronic state in a SiO_x（1.4-2.3 nm）/c-Si（150 μm） interface has been investigated.This occurred in the process of depositing indium tin oxide（ITO） film onto the silicon substrate by magnetron sputtering.We observe that this damage is caused by energetic particles produced in the plasma（atoms,ions,and UV light）.The passivation quality and the variation on interface states of the SiO_x/c-Si system were mainly studied by using effective minority carrier lifetime（τ_（eff）） measurement as a potential evaluation.The results showed that the samples＇ τ_（eff）was reduced by more than 90%after ITO formation,declined from 107 μs to 5 μs.Following vacuum annealing at 200 ℃,the τ_（eff） can be restored to 30 μs.The components of Si to O bonding states at the SiO_x/c-Si interface were analyzed by x-ray photoelectron spectroscopy（XPS） coupled with depth profiling.The amorphous phase of the SiO_x layer and the ＂atomistic interleaving structure＂ at the SiO_x/c-Si interface was observed by a transmission electron microscope（TEM）.The chemical configuration of the Si-O fraction within the intermediate region is the main reason for inducing the variation of Si dangling bonds（or interface states） and effective minority carrier lifetime.After an appropriate annealing,the reduction of the Si dangling bonds between SiO_x and near the c-Si surface is helpful to improve the passivation effect.
