Recently, hydrovoltaic technology emerged as a novel renewable energy harvesting method, which dramatically extends the capability to harvest water energy. However, the urgent issue restricting its device performance is poor carrier transport properties of the solid surface if large charged interface is considered simultaneously. Herein, a hydrovoltaic device based on silicon nanowire arrays (SiNWs), which provide large charged surface/volume ratio and excellent carrier transport properties, yields sustained electricity by a carrier concentration gradient induced by evaporation‐induced water flow inside nanochannels. The device can yield direct current with a short‐circuit current density of over 55 μA cm−2, which is three orders larger than a previously reported analogous device (approximately 40 nA cm−2). Moreover, it exhibits a constant output power density of over 6 μW cm−2 and an open‐circuit voltage of up to 400 mV. Our finding may pave a way for developing energy‐harvesting devices from ubiquitous evaporation‐driven internal water flow in nature with semiconductor material of silicon.
material. Graphene has been demonstrated to be an effective channel material for phototransistor because of its broadband light absorption, fast response time, and ultrahigh carrier mobility. [1][2][3] However, the relatively low absorption cross-section, fast recombination rate and the absence of gain mechanism that can generate multiple charge carriers from one incident photon have limited the responsivity of pure graphene-based phototransistor [ 4,5 ] to ≈10 −2 A W −1 which is much lower than that of commercial Si photodiode. [ 6 ] So far, the rapid development of graphene-based photodetection has focused on enhancement of the light absorption in graphene by variant approaches such as plasmonic coupling [ 7 ] and microcavity confi nement. [8][9][10] Nevertheless, a key to ultrasensitive graphene-based photodetection is the implementation of photoconductive gain which could afford the ability to generate multiple electrical carriers per single incident photon.Until now, the photoconductive gain for improved sensitivity has not been observed in pure grapehene-based photodetector. Alternatively, the hybridization of graphene with a gain material or the formation of a heterostructure has been proved to be an effective approach to enhance the photodetection performance. For example, the mixtures of graphene with TiO 2 [ 11 ] or quantum dots [ 12 ] have shown greatly improved photoconductive gain but the synthesis of gain material needs complicated processes. The formation of vertical heterostructure of graphene and layered transition metal dichalcogenides (TMDs) such as MoS 2 , [ 13,14 ] WS 2 , [ 15 ] and WSe 2 [ 16,17 ] can achieve very high quantum effi ciency upon light illumination due to effective photoexcited carrier separation at the interface. However, the fabrication of these devices is expensive and lack of scalability as it demands delicately controlled sample transfer technique which has low-yield and multiple lithography procedures.Recently, mixed organic-inorganic halide perovskites have emerged as a new class of light harvesting material for highly effi cient solar cells with confi rmed effi ciency of 19.2%. [ 18 ] This family of perovskite materials take the form of ABX 3 (A = CH 3 NH 3 + ; B = Pb 2+ ; X = Cl − /I − /Br − ) and show large absorption cross-section, long photocarrier diffusion length, and high charge carrier mobility. [ 19 ] These unique photoelectrical properties enable many photonic and optoelectronic applications such as random lasing, [ 20 ] light emitting diode, [ 21 ] and Graphene is an attractive optoelectronic material for light detection because of its broadband light absorption and fast response time. However, the relatively low absorption cross-section, fast recombination rate, and the absence of gain mechanism have limited the responsivity of pure graphene-based phototransistor to ≈10 −2 A W −1 . In this work, a photoconductive gain of ≈10 9 electrons per photon and a responsivity of ≈6.0 × 10 5 A W −1 are demonstrated in a hybrid photodetector that consists of monolayer g...
Direct electricity generation from water flow/evaporation, coined hydrovoltaic effect, has recently attracted intense interest as a facile approach to harvest green energy from ubiquitous capillary water flow or evaporation. However, the current hydrovoltaic device is inferior in output power efficiency compared to other renewable energy devices. Slow water evaporation rate and inefficient charge collection at device electrodes are two fundamental drawbacks limiting energy output efficiency. Here, we report a bioinspired hierarchical porous fabric electrode that enables high water evaporation rate, efficient charge collection, and rapid charge transport in nanostructured silicon-based hydrovoltaic devices. Such an electrode can efficiently collect charges generated in nanostructured silicon as well as induce a prompt water evaporation rate. At room temperature, the device can generate an open-circuit voltage (V oc) of 550 mV and a short-current density (J sc) of 22 μA·cm–2. It can output a power density over 10 μW·cm–2, which is 3 orders of magnitude larger than all those reported for analogous hydrovoltaic devices. Our results could supply an effective strategy for the development of high-performance hydrovoltaic devices through optimizing electrode structures.
Recently, hydrovoltaic technology emerged as a novel renewable energy harvesting method, which dramatically extends the capability to harvest water energy. However, the urgent issue restricting its device performance is poor carrier transport properties of the solid surface if large charged interface is considered simultaneously. Herein, a hydrovoltaic device based on silicon nanowire arrays (SiNWs), which provide large charged surface/volume ratio and excellent carrier transport properties, yields sustained electricity by a carrier concentration gradient induced by evaporation‐induced water flow inside nanochannels. The device can yield direct current with a short‐circuit current density of over 55 μA cm−2, which is three orders larger than a previously reported analogous device (approximately 40 nA cm−2). Moreover, it exhibits a constant output power density of over 6 μW cm−2 and an open‐circuit voltage of up to 400 mV. Our finding may pave a way for developing energy‐harvesting devices from ubiquitous evaporation‐driven internal water flow in nature with semiconductor material of silicon.
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