Table 1.

Applications of paper and the corresponding electronic and/or optical characteristics.

Applications	Possible use of paper	Brief description of representative research
Photovoltaics	Antireflection coatings[53, 54] or substrates[36, 57–65]	Micro-sized cellulose paper as an antireflection coating for photovoltaics: increased absorption due to index contrast and surface texturing when a transparent paper is applied atop a high index semiconductor (e.g., silicon (Si), gallium arsenide (GaAs)) or a low index polymer substrate, ≈ 24 % enhancements in the power conversion efficiency (η) of a GaAs solar cell[53, 54]
		Cellulose nanocrystals-based paper as a substrate for an organic solar cell: short-circuit current density (JSC) of 16.1 mA/cm2, open circuit voltage (VOC) of 0.68 V, fill factor (FF) of 54 %, and power conversion efficiency of 2.7 %[59]
		Hydrophilic mesoporous material coated ultrasmooth cellulose paper as a substrate for a flexible indoor solar cell: short-circuit current density of 10.19 mA/cm2, open circuit voltage of 0.82 V, fill factor of 40.7 %, and power conversion efficiency of 3.4 %[65]
Electronic circuits	Substrate,[41, 66–93] gate dielectric of field effect transistors (FETs),[41, 92–97] tunnel barrier of memory devices,[98, 99] or electrolyte[100]	Nanofibrillated cellulose (NFC)-based nanopaper as a substrate of an organic FET: effective carrier mobility of 4.3 × 10−3 cm2/V·s, drain-source current on/off modulation ratio of 200[77]
		Ultrasmooth and clear nanopaper made of NFC acts as a substrate for In–Ga–ZnO/Al2O3 thin-film transistors (TFTs): saturation mobility of 15.8 cm2/V·s, on/off modulation ratio of 4.4 × 105, threshold voltage of −0.42 V, and a subthreshold gate voltage swing of 0.66 V per decade[90]
		Paper as a gate dielectric layer of a flexible FET: effective carrier mobility of > 30 cm2/V·s, drain-source current on/off modulation ratio of 104, a near-zero threshold voltage, and a subthreshold gate voltage swing of 0.8 V per decade[94]
Transparent conductive electrodes	Electrodes[14, 56, 61, 101–121]	Silver nanowires-coated cellulose nanofibers as a transparent conductive electrode for light-emitting diodes or solar cells: high optical transmission of > 90 % and good conductivity while maintaining stable operation under bending[118]
		Metal nanotrough networks coated on paper: high optical transmission of > 90 % and low sheet resistance of ≈ 2 Ω per square, superior optical transmittance in near-infrared (NIR) range where conventional transparent conductive electrodes (e.g., indium tin oxide) are opaque[103]
Displays	Substrates for OLEDs[42, 122–131] or touch screens[55, 56]	Flexible cellulose nanocomposites as substrates for an OLED: low coefficient of thermal expansion, high optical transmittance (> 82 %) in the visible spectrum[123]
		Transparent nanopaper-based substrate for a highly flexible OLED: strong mechanical properties with a maximum loading stress of 200 MPa to 400 MPa, low coefficient of thermal expansion (2.7 μm/m/K), high optical transmittance (> 93 %) at a wavelength of 550 nm[126]
		Plastic-paper hybrid structure as a substrate for an OLED: high optical transmittance of > 85 % and haze of > 90 %, more than 35.1 % improved power efficiency compared to an OLED on plastic or glass substrate[42]
Energy storage	Electrodes,[108–114, 116, 132–147] separators,[101, 132, 134, 148, 149] reservoir,[150, 151] or substrate[152]	Filter paper as an electrode of a supercapacitor: an areal capacitance of 700 mF/cm2 at a scan rate of 5 mV/s with maintaining capacity more than 85 % over 1000 cycles (at a current density of 20 mA/cm2)[144]
		Conductive nanopaper as counter/reference electrodes of a lithium (Li)-ion battery: 1200 mA·h/g for 100 cycles[139]
Antennas	Substrates[153–166]	30 nm cellulose nanofibers-based paper as a substrate of a foldable antenna: return losses of −26.7 dB on compressed pulp paper, transmission and reception of multiple frequencies by folding the paper-based antenna[160]
		A nanopaper composite as a substrate of a flexible antenna: a minimum return loss at 2.6 GHz for Wi-Fi communication[162]