Radiative recombination coefficient in crystalline silicon at low temperatures < 77 K by combined photoluminescence measurements

Rudolf Brüggemann (1) , Ming Xu (1) , José Alvarez (1) , Mohamed Boutchich (1) , Jean-Paul Kleider (1)

1 GeePs - Laboratoire Génie électrique et électronique de Paris

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract Spectral photoluminescence (sPL) and modulated photoluminescence (MPL) measurements were applied to determine the band-to-band radiative recombination coefficient, B rad , in crystalline silicon. We used precursors of n-type crystalline silicon solar cells consisting of two different wafers passivated with aluminum oxide stacks or intrinsic hydrogenated amorphous silicon, respectively. So far values for B rad can be found in the literature only above 77 K. In this high-temperature range the temperature dependence of B rad obtained using our combined sPL/MPL method is in good agreement with the available literature data for both samples. Interestingly, we have extended the measured range down to a temperature of 20 K and observed a strong increase of B rad by three orders of magnitude with decreasing temperature from 77 K to 20 K.

Mots clés: Heat demand; Forecast; Climate change Keywords: silicon; radiative recombination; recombination coefficient; photoluminescence

Domaines: Sciences de l'ingénieur [physics]

Rudolf Brüggemann, Ming Xu, José Alvarez, Mohamed Boutchich, Jean-Paul Kleider. Radiative recombination coefficient in crystalline silicon at low temperatures < 77 K by combined photoluminescence measurements. Energy Procedia, 2017, 124, pp.10 - 17. ⟨10.1016/j.egypro.2017.09.331⟩. ⟨hal-01631793⟩