Upconversion solar cell measurements under real sunlight

Abstract

The main losses in solar cells result from the incomplete utilization of the solar spectrum. Via the addition of an upconverting layer to the rear side of a solar cell, the otherwise-unused subbandgap photons can be utilized. In this paper, we demonstrate an efficiency enhancement of a silicon solar cell under real sunlight due to upconversion of sub-bandgap photons. Sunlight was concentrated geometrically with a lens with a factor of up to 50 suns onto upconverter silicon solar cell devices. The upconverter solar cell devices (UCSCDs) were also measured indoors using a solar simulator. To correct for differences in the spectral distribution between real sunlight and the solar simulator a spectral mismatch correction is required and is especially important to properly predict the performance when a non-linear response (e.g. upconversion) is involved. By applying a spectral mismatch correction, good agreement between the solar simulator measurements and the outdoor measurements using real sunlight was achieved. The method was tested on two different upconverter powders, -NaYF4: 25% Er 3+ and Gd2O2S: 10% Er 3+ , which were both embedded in a polymer. We determined additional photocurrents due to upconversion of 9.4 mA/cm 2 with -NaYF4 and 8.2 mA/cm 2 with Gd2O2S under 94-suns concentration. Our results show i) the applicability of measurements using standard solar cell characterization equipment for predicting the performance of non-linear solar devices, and ii) underline the importance of applying proper mismatch corrections for accurate prediction of the performance of such non-linear devices.

Doping Lanthanide Ions in Colloidal Semiconductor Nanocrystals for Brighter Photoluminescence

“…[12][13][14] In the field of photovoltaics they can provide the additional boost to overcome the Shockley-Queisser limit. 15,16 Aside from the technological relevance of nanomaterials based on these elements, as scientists we are also genuinely mesmerized by their luminescence: the complex physical processes governing it are source of continue wonder, pushing us to a pursue their deeper understanding.…”

Ап-конверсия инфракрасного излучения в щелочно-земельных фторидах, активированных Er-=SUP=-3+-=/SUP=-

“…Высокий выход свечения при 990 nm позволяет пытаться применить эти материалы для повышения эффективности кремниевых солнечных батарей. Такие исследования для материалов, содержащих Er 3+ , интенсивно проводятся последние годы [1,9,14]. Зависимость прироста тока j в кремниевом солнечном элементе от интенсивности C инфракрасного излучения солнца, конвертированного в излучение ∼ 980 nm, описывается выражением j = aC b , где коэффициент b равен 1.55 для β−NaYF 4 [9] и 1.59 для Gd 2 O 2 S [14].…”

“…Помимо видимых полос свечения, возбуждение лазерным излучением 1.5 µm приводит к появлению свечения в области 990 nm (CdF 2 −Er [6], CaF 2 −Er [8]), интенсивность которого превышает интенсивности видимых полос. По этой причине некоторые фторидные материалы предлагались для повышения выхода кремниевых фотопреобразователей [1,8,9].…”

Characterization of Plasmonic Scattering, Luminescent Down-Shifting, and Metal-Enhanced Fluorescence and Applications on Silicon Solar Cells

“…Materials must be selected carefully to minimize mismatch between the solar spectrum and the spectral absorption of solar cell (spectral losses). One approach to expand the usable range of light involves the application of a conversion layer, such as down conversion (DC) [18,19], down shifting (DS) [20,21], up conversion (UC) [22,23], and multi-junction tandem structures [24,25]. DC involves converting an incident high-energy photon (UV-blue wavelengths) into two or more photons of lower energy (within visible wavelengths).…”