ITO-Free Transparent Organic Solar Cell with Distributed Bragg Reflector for Solar Harvesting Windows

Abstract

We demonstrated an indium tin oxide (ITO)-free, highly transparent organic solar cell with the potential to be integrated into window panes for energy harvesting purposes. A transparent, conductive ZnO/Ag/ZnO multilayer electrode and a Ag:Ca thin film electrode were used in this transparent device as the bottom and top electrode, respectively. To further improve the transmittance of the solar cell, the thickness of the top ZnO layer was investigated both experimentally and with simulations. An average visible transmittance of >60% was reached, with a maximum transmittance of 73% at 556 nm. Both top and bottom illumination of the solar cell generated comparable power conversion efficiencies, which indicates the wide application of this solar cell structure. In addition, we fabricated distributed Bragg reflector mirrors with sputtered SiO 2 and TiO 2 , which efficiently increased the power conversion efficiency over 20% for the solar cells on glass and poly(ethylene terephthalate) (PET) substrates.

Vacuum‐Deposited Transparent Organic Photovoltaics for Efficiently Harvesting Selective Ultraviolet and Near‐Infrared Solar Energy

“…The recent reports (AVT vs PCE vs LUE plot) on the thin‐film type TPVs with a UV or UV/NIR‐selective mode. [ 8,9,13,15,16,58–72 ] Note that the proposed ClAlPc:C 60 TPV with AVT of 77.45% and PCE of 1.34% has been demonstrated in this work.…”

“…Accordingly, we would like to use the parameters of the AVT, PCE, and light utilization efficiency (LUE = PCE × AVT), as shown in Figure , to directly evaluate our TPV devices’ performance and compare with the TPV devices proposed by other groups. [ 8,9,13,14,16,58–72 ] As the AVT of our proposed TPV device is approaching >75%, the amount of photons absorbed by the active layer is insufficient, resulting in the poor PCE and LUE values. However, compared with other groups’ results, our TPV device still shows the highest AVT while maintaining the PCE at 1.34% and the LUE at 1.03.…”

Transparent Power‐Generating Windows Based on Solar‐Thermal‐Electric Conversion

“…The PCE values of some TPV technologies from literature are also plotted for comparison. [ 9,11,21,32–35 ]…”

“…As is shown in Figure 4c, when average visible transmission (AVT) (Table S1, Supporting Information) reaches 70%, the PCE of our TSTE technology is around 0.4%, which is comparable to that of reported TPV technologies. [ 9,11,21,32–35 ] Moreover, the PCE will reach up to 0.8% if ideal heat‐transfer conditions are achieved with the materials used in this work. More importantly, we can independently regulate the power conversion efficiency and transparency of the window, which means that by using the thermoelectric materials with higher zT values, PCE values can be significantly enhanced without impairing AVT (Figure 4c and Figure S18, Supporting Information).…”

Realizing 8 cd A−1 Current Efficiency for Solution-Processed Inverted Top-Emitting Polymer Light-Emitting Diodes

“…However, in most of the TOLED architectures, the light is extracted through a semitransparent electrode such as silver or aluminum. The transmittance in UV-visible range of thin metallic layers (50-60%) [7][8][9] is low compared to ITO (> 80%), 10 which drastically decreases the OLED light outcoupling. It has been widely shown experimentally 7,9,11 and theoretically, 7,9 that the transmittance of thin metallic layers can be enhanced by using a trilayer stack, such as molybdenum oxide/silver/molybdenum oxide (MoO x /Ag/ MoO x ) stacks, widely used in top-illuminated solar cells 7,12,13 and semi-transparent devices.…”