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

Abstract

Highly transparent photovoltaics (TPVs) integrated to a battery with small capacity can efficiently drive low‐powered internet of things (IoT) devices such as the receivers, sensors, actuators, etc. Such see‐through solar technology not only provides an opportunity to convert ambient light (sunlight or indoor lighting) to electricity but also demonstrates a concept of self‐sustainable power. In this work, a selective ultraviolet/near‐infrared bulk‐heterojunction active layer, i.e., chloroaluminum phthalocyanine (ClAlPc) as donor and C60 as acceptor with a Cu:Ag/WO3 transparent electrode to visible lights are combined for achieving the vacuum‐deposited TPVs with a power conversion efficiency of 1.34%, average visible transmission of 77.45%, and color rendering index of 91.9. Moreover, a TPV module with a working area of 1.5 cm2 is able to charge a 0.58 mAh LiFePO4(LFP)//Li battery fully within one hour under 100 mW cm‐2 (≈1 sun) illumination. The TPV module can drive an exciplex organic light‐emitting diode with the electroluminescence >180 cd m−2 at low illumination intensity of <5 mW cm‐2. Overall, this work presents a significant step forward in the development of TPV technology towards integrating a display and storage battery, which could be successfully applied in wearable electronics requiring invisible and sustainable solar power.

Transparent organic upconversion devices displaying high-resolution, single-pixel, low-power infrared images perceived by human vision

“…In the presence of an infrared stimulus, photoinduced hole carriers travel to the EML guided by the external field for charge recombination. To selectively band-pass the upconversion visible light while harnessing incident infrared photon, a semitransparent copper-silver alloy thin film (Cu:Ag, 1:50) ( 32 ) capping with WO 3 layer was introduced as the top cathode to preserve an average visible transmittance (AVT) approaching 60% for the overall device stacking.…”

“…Despite holding great promise, how much the upconversion luminance, or the deduced η p-p , can be preserved after comprising a semitransparent top-emissive cathode remains crucial. Because a semitransparent metal alloy alleviates the surface scattering loss from localized plasmon resonance effect in the NIR region ( 32 ), we replaced the standard Ag cathode (100 nm) with Cu:Ag alloy thin film (12 nm) capped with the index-matching WO 3 layer for the top-emissive structure. Although further reducing the alloy thickness can, on the one hand, achieve higher transmittance in visible frequency, it undermines the wavelength selectivity for the reflective infrared signal, as well as the uniformity concern on the other hand.…”

Using 3.0 eV Large Bandgap Conjugated Polymer as Host Donor to Construct Ternary Semi‐Transparent Polymer Solar Cells: Increased Average Visible Transmittance and Modified Color Temperature

“…Several optical engineering methods via inserting antireflection layer and outcoupling layer, changing transparent electrode, etc., have been utilized to optimize the performance of ST-OSC. [4,[13][14][15][16][17][18][19][20][21][22][23][24][25][26] A recent study indicates that inserting anti-reflection layer for ST-OSC can dramatically elevate the AVT from 26.16% to 41.08%, leading to obviously improved LUE from 3.02 to 4.46. [27] However, judicious selection of the active layer materials should be more direct and basic, [28,29] and optical engineering is typically carried out based on some notable active layers so as to further enhance the performance of ST-OSC.…”

Synthesizing Near‐Ultraviolet‐Absorbed Donor for Transparent Polymer Solar Cells

“…Even so, the reported works utilizing near‐ultraviolet absorbers have been mainly focused on vacuum‐vapor transparent organic solar cells utilizing near‐ultraviolet absorbed small‐molecule donor until now, providing highly transparent (AVT > 65%) and low‐visible tinted (CRI > 90) organic solar cells with relatively low power output merely appropriate to low‐power multifunctional windows. [ 16,23–26 ] The challenge comes from the achievement of transparent near‐ultraviolet absorbent polymer donors which could well function as the common “D–A”‐type polymer donors, such as PM6, D18 and PCE10, in terms of charge carrier transport, energy‐level matching, and miscibility with the acceptor. [ 27–29 ] In recent times, Tang et al reported a transparent all‐small‐molecule organic solar cell via solution processing method with the best AVT of around 48% and a remarkable PCE of 3.01% using an ultrawide‐bandgap TAPC molecule ( E g ≈ 3.4 eV) as the small‐molecule donor and Y6 molecule as the narrow‐bandgap NF‐SMA ( E g = 1.33 eV).…”