In conventional crystalline silicon （Si） homojunction solar cells,a strategy of doping by transporting phosphorus or boron impurities into Si is commonly used to build Ohmic contacts at rear electrodes.However,this ...In conventional crystalline silicon （Si） homojunction solar cells,a strategy of doping by transporting phosphorus or boron impurities into Si is commonly used to build Ohmic contacts at rear electrodes.However,this technique involves an energy intensive,high temperature （～ 800 ℃） process and toxic doping materials.Black phosphorus （BP） is a two-dimensional,narrow bandgap semiconductor with high carrier mobility that exhibits broad light harvesting properties.Here,we place BP：zinc oxide （ZnO） composite films between Si and aluminum （Al） to improve their contact.Once the BP harvests photons with energies below 1.1 eV from the crystalline Si,the ZnO carrier concentration increases dramatically due to charge injection.This photo-induced doping results in a high carrier concentration in the ZnO film,mimicking the modulated doping technique used in semiconductor heterojunctions.We show that photo-induced carriers dramatically increase the conductivities of the BP-modified ZnO films,thus reducing the contact resistance between Si and Al.A photovoltaic power conversion efficiency of 15.2% is achieved in organic-Si heterojunction solar cells that use a ZnO：BP layer.These findings demonstrate an effective way of improving Si/metal contact via a simple,low temperature process.展开更多
基金This work was supported by the National Basic Research Program of China （973 Program） （No. 2012CB932402）, National Natural Science Foundation of China （Nos. 91123005 and 61674108）, Jiangsu Key Laboratory for Carbon-Based Functional Materials ＆ Devices, the Priority Academic Program Development of Jiangsu Higher Education Institutions and Collaborative Innovation Centre of Suzhou Nano Science and Technology.
文摘In conventional crystalline silicon （Si） homojunction solar cells,a strategy of doping by transporting phosphorus or boron impurities into Si is commonly used to build Ohmic contacts at rear electrodes.However,this technique involves an energy intensive,high temperature （～ 800 ℃） process and toxic doping materials.Black phosphorus （BP） is a two-dimensional,narrow bandgap semiconductor with high carrier mobility that exhibits broad light harvesting properties.Here,we place BP：zinc oxide （ZnO） composite films between Si and aluminum （Al） to improve their contact.Once the BP harvests photons with energies below 1.1 eV from the crystalline Si,the ZnO carrier concentration increases dramatically due to charge injection.This photo-induced doping results in a high carrier concentration in the ZnO film,mimicking the modulated doping technique used in semiconductor heterojunctions.We show that photo-induced carriers dramatically increase the conductivities of the BP-modified ZnO films,thus reducing the contact resistance between Si and Al.A photovoltaic power conversion efficiency of 15.2% is achieved in organic-Si heterojunction solar cells that use a ZnO：BP layer.These findings demonstrate an effective way of improving Si/metal contact via a simple,low temperature process.
