Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

Abstract

Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From "dye" in dye sensitized solar cells to "hole conductors" and "electron conductors" in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Grätzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after the demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH 3 NH 3 PbI 3 (MAPbI 3) polycrystalline thin films. This review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically

Graphene‐Based Electron Transport Layers in Perovskite Solar Cells: A Step‐Up for an Efficient Carrier Collection

“…In the last decade, hybrid organic-inorganic materials with the perovskite structure, most notably CH 3 NH 3 Pb(I,Cl) 3 , have become the most promising light-harvesting active layer for the implementation of high efficiency and low cost solar cells [1][2][3][4][5][6][7][8] . As a matter of fact, the power conversion efficiency of perovskite solar cells (PSCs) has shown a very fast growth, increasing from 3.8% 9 in 2009 to 22.1% 10 in 2016.…”

“…Moreover, a high density of trap states, both on surfaces and in grain boundaries 3,[16][17][18] , are present in polycrystalline perovskites, used for solar cells and light emitters. Indeed, even though theoretical predictions show that deep trap states are not generally formed inside perovskites grains, the opposite is observed at the grain boundaries and at the surfaces 3,19 . Therefore, sophisticated passivation strategies are essential for increasing the efficiency of PSCs and light emitters [19][20][21][22] .…”

Controlled Deposition and Performance Optimization of Perovskite Solar Cells Using Ultrasonic Spray‐Coating of Photoactive Layers

“…[5,6] Up to now, the fabrication of high-quality perovskite films with controlled morphology,h igh surfacec overage, and al arge grain domain for high-performance solution-processed perovskite solar cells is still challenging.Avariety of effective approaches to manipulate the growth of perovskite crystals in solution-processed systems, especially in the planer heterojunction, to achievet he optimized morphologyh ave been thoroughly investigated. [7][8][9] The desired perovskite-film deposition andc rystalline formation can be obtained by adopting suitable deposition methods (one-, two-, or multi-step) [10][11][12][13][14] and tuning precursor-related parameters (solution concentration, [15,16] precursor ratio, [17][18][19][20] and professional solvent engineering), [21][22][23][24] solution-coating variables [25][26][27][28][29] (processing/post-processing temperature/time, etc), interfacial engineering, [30][31][32] etc.…”

Interdigitated Hierarchical Integration of an Efficient Lateral Perovskite Single‐Crystal Solar Cell

“…[6] Moreover,t hese OTPs with their impressive and promisingc haracteristics are also an appealing material for photodetectors, [7] light-emitting diodes, [8] and lasers [9] because of their versatile attributes such as excellent charge-carrier mobility (10 1 cm 2 V À1 s À1 ), absorption coefficients (10 5 cm À1 ), flexibility and scalability of thin-film fabrication andt unable optoelectronic characteristics. [10][11][12][13][14] Conventional perovskite photovoltaic devices involve films grown in layersv ertically one after another on rigid transparent electrode substrates (e.g.,i ndium tin oxide;I TO) in which inherentg aps occur from the wiping out of at hin subsurface layer by using solvents. They have high costs, 20 %l ight loss caused by transmittance/scattering, andt he inflexibility and brittleness of the glasses.…”